PLAISTOW, N.H. — Sen. Joe Lieberman’s (Conn.) message to the crowd assembled at Timberland High School on Wednesday was simple: His years of experience in government coupled with a long record of bipartisan cooperation make him the Democratic candidate best able to beat President Bush.

“You don’t have to look at slick 30-second television commercials to know what kind of president I will be,” he said. “You can look at a 30-year record of public service.”

Unfortunately for the Connecticut Senator, at least two-thirds of the audience was not even born three decades ago and more than half were under 18 — and not even able to vote for him in next Tuesday’s first-in-the-nation primary.

After making a strategic decision to skip the Iowa caucuses, he has seen both Sens. John Kerry (Mass.) and John Edwards (N.C.) speak to overflow crowds here in recent days as they feed off the momentum gained from their surprisingly strong showings in the Hawkeye State — as Lieberman toils in relative obscurity seeking a breakthrough with voters.

At a packed chili feed in Pembroke on Tuesday night, Kerry took a confident tone after his Iowa victory, expending the vast majority of his rhetorical firepower on President Bush.

“I come here to mark the beginning of the end of the Bush presidency,” he said.

In spite of his colleagues’ growing strength in the state, Lieberman maintained Wednesday that the New Hampshire race remains wide open and repeatedly cited his long government service as the trait that will spark voter movement on his behalf.

“The first-in-the-nation primary is totally undecided,” Lieberman said at the close of his speech in Plaistow, noting that in some surveys as much as half of the electorate has not settled on a candidate. “Granite Staters are not going to rush to conclusions.”

That sentiment was echoed by Kathy Elliott, a secretary who sat in the front row for Lieberman’s speech.

“I have lived in New Hampshire for 10 years and the one thing I have learned is that the people of New Hampshire think independently,” she said.

While Elliott said she was “very impressed” with Lieberman and praised his stance on the Iraq war and its aftermath, she admitted that he had not yet won a convert. “I just haven’t decided yet,” she said.

Time is running short for Lieberman, who remains mired in single digits behind Kerry and Edwards as well as retired Gen. Wesley Clark and former Vermont Gov. Howard Dean in a variety of tracking polls that have been released in New Hampshire this week.

A Boston Herald poll released Wednesday gave Kerry a 10-point lead over Dean, 31 percent to 21 percent. Clark had dropped to 16 percent, Edwards was at 11 percent and Lieberman was stuck at 4 percent.

In order for Lieberman to show well here, his campaign acknowledges, he must peel off Independents and Republicans, both of whom are allowed to vote under the state’s open primary laws.

Seeking to appeal to these independents, Lieberman twice invoked the name of Sen. John McCain (R-Ariz.), who in 2000 utilized strong support from unaffiliated New Hampshire voters to topple George W. Bush in the GOP presidential primary. Bush recovered, however, to secure the Republican nomination and then the presidency itself.

“I have the ability to get support from Democrats, Independents and disgruntled Republicans,” said Lieberman, who added that to beat Bush in November Democrats need a candidate who can “hold the party together and add votes to it.”

Lieberman said Wednesday that even if he finishes worse than third in New Hampshire he will continue his campaign and fight for the seven states that hold primaries or caucuses on Feb. 3. Several states that vote on that day — most notably South Carolina and Oklahoma — are seen as more moderate and hence more receptive to Lieberman’s message of centrism.

Despite his assertions, a fourth-place finish in New Hampshire would be potentially devastating for Lieberman, who has dedicated massive amounts of time and resources to the state — even going as far as to become a temporary resident by recently moving into an apartment in the state.

Lieberman’s spadework has paid some dividends.

During a raucous late-afternoon rally at his headquarters in downtown Manchester on Wednesday, supporters toted signs that proclaimed “We are hot for Joe (and Hadassah too).” The chants grew louder as the candidate leapt out of a white Ford Explorer and campaigned down Elm Street flanked by a horde of television cameras.

The throng passed Caesario’s Pizza, which was made famous by a surprise visit from President Bush during an October campaign stop. There were photos of two Democratic candidates — Lieberman and Clark — plastered beside Bush.

The question that remains unanswered is whether Lieberman’s presence in the state can trump the sudden energy generated by his rivals’ campaigns.

Although New Hampshire voters proudly deny that the results of the Iowa caucuses have any effect on their vote, Kerry is clearly surging in New Hampshire due in no small part to his victory in Iowa.

At Kerry’s event Tuesday night, Deborah Karr sat eating chili from a Styrofoam cup with a Dean for America sticker on her chest but with doubts about her choice lingering in her mind.

“I have been volunteering for Dean but I wanted to hear what Kerry has to say,” Karr said. “I need to support whoever is going to beat President Bush.”

Clearly aware of his potential to make inroads with wavering Dean supporters, Kerry obliquely referred to the former Vermont governor in his remarks.

“We must offer this country real answers, not anger — solutions, not sound bites,” Kerry said.