A University of New Hampshire poll released yesterday showing Sen. John Sununu climbing into a statistical dead heat with Jeanne Shaheen and Carol Shea-Porter losing to one potential GOP challenger is apparently causing angst among Democrats.

UNH's polling technique is being questioned on the liberal blog BlueHampshire.com, which began disparaging its methods on Tuesday, about seven hours before it was released. A writer there said UNH's polls have "serious sampling problems." Too many Republicans are being included, apparently, at least for BlueHampshire's liking.

We have no intention of defending polls by UNH or anyone else. We'll simply take a look at the numbers and poll director Andrew Smith's explanation of how he arrives at those numbers.

But if this poll is accurate, it's the best news Republicans in these parts have seen in more than two years.

Shaheen-Sununu

UNH polled 519 "randomly selected New Hampshire adults" from July 11 through July 20, including 475 who said they were registered voters. The margin of error is 4.5 percent.

It showed Shaheen leading Sununu 46 to 42 percent with 10 percent undecided and 1 percent favoring some other candidate. That's within the margin of error -- a statistical dead heat.

A UNH poll released in May had Shaheen with a 12 percentage point lead, 52 to 40 percent with only 7 percent undecided and 1 percent for someone else. In February, a UNH poll had Shaheen ahead by 17 percentage points.

The new poll showed the race very much in flux, with only 22 percent of likely voters saying they have definitely decided who they will vote for, 6 percent leaning toward a candidate and 72 percent still trying to decide who to support. That huge "still deciding" number is 67 percent of the self-identified Democrats polled, 70 percent of the self-identified Republicans and 93 percent of the self-identified independents.

In 1st Congressional District trial heats, UNH has Democratic incumbent Shea-Porter narrowly trailing Republican former congressman Jeb Bradley, 46 to 40 percent with 14 percent undecided. It showed Shea-Porter leading Republican John Stephen 42 to 36 percent, with 21 percent undecided.

Those races are virtually unchanged since the May poll, when Bradley led Shea-Porter 45 to 39 percent and Shea-Porter led Stephen 43 to 35 percent.

The new poll has 2nd CD Democratic incumbent Paul Hodes comfortably leading both Republicans Bob Clegg, 44 to 25 percent with 29 percent undecided, and Jennifer Horn, 43 to 23 percent with 32 percent undecided.

The sampling for the 1st District is 235 voters, and 240 for the 2nd District -- both small enough for the margins of error to be a wide 6.4 and 6.3 percent, respectively. And that means Shea-Porter is in a statistical tie with both Bradley and Stephen.

If there is any discomfort for Hodes in the poll, it's that even as an incumbent with nearly $1 million on hand running against Republicans with far less name recognition, he fails to break the 50 percent plateau.

Shea-Porter, who was the political "story" of the week last week with her huge fundraising success in the second quarter, has another bit of trouble, according to this poll -- her "favorable-unfavorable" rating.

Only 35 percent of those polled in her district view her favorably, while 32 percent view her unfavorably. In the May poll, her "favorable-unfavorables" were 39 and 28 percent, respectively.

By comparison, Sununu is viewed favorably by 52 percent of those polled and unfavorably by 33 percent. Shaheen's favorable rating is 53 percent, with 31 percent unfavorable.

Sen. Judd Gregg, by the way, is viewed favorably by 53 percent with 23 percent viewing him unfavorably.

The May poll had Sununu at 48-37 percent favorable-unfavorable and Shaheen at 56-29 percent.

The sample

Poll director Smith says his sample is chosen purely at random. He said he screens only for demographics -- such as age, gender and education levels -- and geographically, to get an accurate representation of various regions of the state.

But he said he does not screen for political party. The sample's political makeup "chooses itself," he said.

"Research has shown that weighting by party is misleading because you have to guess what the electorate is going to look like on election day, and that is difficult to do based on past election history," he said.

Smith said that all those surveyed were asked near the end of their interviews, "Generally speaking, do you usually consider yourself a Democrat, Republican, independent or what?" He said the terms "Republican," "Democrat" and "independent" are rotated.

The result is "self-identified" Republicans, Democrats and independents, which never match up with the breakdown by registration.

In the new poll, those who chose between Shaheen and Sununu identified themselves in this way: 189 Democrats, 192 Republicans and 63 independents. But Smith said that many of the Democrats and Republicans were actually registered as undeclared, or independent, voters.

The same race had this sample for registered voters: 120 registered Democrats, 130 registered Republicans and 186 registered independents.

Smith called voter self-identification "the biggest predictor of voting variations."

A fall 2006 poll with 515 respondents that showed Gov. John Lynch crushing challenger Jim Coburn (which he did in the election) included 185 self-identified Democrats, 170 self-identified Republicans and 81 self-identified independents, although the registered breakdown was 108 Democrats, 169 undeclared and 114 Republicans.

"In 2006," Smith said, "I was beat up because some said I had too many Democrats in the sample. But you just weight by the demographics and the partisanship, you let fall out as it does. We don't know what people will say that they are with respect to party when we call them. It happens to shake out that way."

So what happened?

Why the tightening in the Senate race?

Smith said that in April, people were paying even less attention to the race that they are today "and were thinking of it as a generic race. They really hadn't put the character of the candidates into play yet."

"Now," he said, "it's John Sununu versus Jeanne Shaheen. Both are well-known candidates and people are starting to associate the names with this race."

In February, Smith said Sununu's chances for reelection "are currently doubtful." In May, Smith said that while he "has closed the gap somewhat, Sununu must be considered the underdog going into the November general election."

Yesterday, Smith said he now expects the Senate race to remain close and "bounce around" until the election.

Strengths, weaknesses

As expected, the UNH poll showed a wide gender split in the Senate race.

Shaheen out-polled Sununu among women, 56 to 32 percent, while Sununu leads among men, 53 to 35 percent.

Self-identified liberals favor Shaheen. Conservatives back Sununu. Moderates back Shaheen, 56 to 34 percent.

Shaheen leads 62 to 30 percent among those 18 to 34 years old; Sununu leads among those 35 to 49 by a margin of 49 to 42 percent; among those 50 to 64 by a margin of 52 to 38 percent and among those 65 and older, 54 to 33 percent.

Sununu leads Shaheen in the 1st Congressional District, 47 to 45 percent, while Shaheen leads in the 2nd District, 48 to 37 percent.

What about Bennett?

Dick Bennett's American Research Group this week had Shaheen leading Sununu by an margin of 58 to 36 percent a day after it, like UNH, showed Sen. John McCain and Sen. Barack Obama tied.

Why the huge disparity between ARG and UNH in the Senate race?

Bennett's explanation is his polling methods are similar to Smith's.

He said that 600 New Hampshire adults are randomly sampled, and, "When we get 600 likely voters, we stop and look at the total population and match the demographics of the estate.

"The party registrations fall where they fall," he said.

In the Senate race, Bennett said his sample included 175 self-described registered Republicans, 179 self-described registered Democrats, and 246 self-described undeclared (independent) voters.

Bennett said 90 percent of those who chose Obama over McCain also chose Shaheen over Sununu, while only two-thirds of the McCain supporters also backed Sununu.

False veep alarm

McCain may well announce his running mate this week, as rumored, but despite a report to the contrary, he offered no hints at his private meeting Tuesday afternoon with the New Hampshire delegation to the Republican National Convention.

CNN said it was told by a Republican source who attended the meeting that McCain, "out of the blue," told the group he thinks they are "really going to like" Minnesota Gov. Tim Pawlenty. CNN said the comment was a "serious hint" that McCain was thinking of making Pawlenty his running mate.

McCain may well name Pawlenty, but it's also a fact that the governor will also be the host of the convention in Minneapolis.

Delegates Peter Spaulding, Steve Duprey, Tom Rath, Jim Merrill and Chuck Douglas all told us yesterday that McCain was talking about Pawlenty's hospitality when he said what he said.

"I certainly didn't take it in any way as any sort of hint for vice president," said Spaulding. "The term 'vice president' didn't even come up."

"The people who are reading the tea leaves are wrong," said Duprey, who was with McCain yesterday in Pennsylvania.

"It wasn't that kind of meeting," said Rath.

According to those on hand, the brief meeting took place at the Wiggins Airways terminal before McCain left the state. McCain shook hands with every delegate, signed autographs, posed for photos and thanked the group for their past and future work on his behalf.

Quick takes

-- Congressional hopeful Stephen picked up a significant endorsement yesterday: New Hampshire Citizens for Life, the state affiliate of the National Right-to-Life Committee, backed him over the pro-choice primary rival Bradley.

-- U.S. District Court Judge Joseph LaPlante today will hear oral arguments on a motion to dismiss Nashua resident Fred Hollander's legal claim that McCain cannot, under the Constitution, be President because he was born in the Panama Canal Zone. The motion was filed by McCain's local attorney, supporter Chuck Douglas.

--Before it shut down earlier this month, Countrywide Home Loans PAC, the political arm of the embattled Countrywide Financial Corp., contributed $3,000 to Sununu, according to his latest financial disclosure.

--2nd District Republican congressional candidate Grant Bosse has filed a complaint with the Federal Election Commission charging that primary foe Jennifer Horn "habitually used general election funds to pay for campaign expenses during the primary," which is prohibited. Horn campaign manager David Chesley called the charge "completely baseless" and accused Bosse of "throwing trash against a wall to see if it sticks."

--Former Hillary Clinton New Hampshire campaign manager Nick Clemons has landed a big post in California heading San Francisco Mayor Gavin Newsom's exploratory committee for his expected run for governor.

-- Republican Hillsborough County Commissioner candidate Pam Manney has picked up the endorsement of outgoing county Registrar of Deeds Judith MacDonald.

--Republican National Committee Co-Chair Jo Ann Davidson will headline the Strafford County Republican Committee's annual picnic on Aug. 3 in Dover.

John DiStaso is senior political reporter of the New Hampshire Union Leader.