Paul's speech comes as the Kentucky Republican weighs a possible run for the White House in 2016 and pushes to strengthen his appeal beyond his father's passionate supporters to prove he can be a credible national candidate.
Republicans are united in their eagerness to propel their candidates into victory this fall, Paul said, including incumbent Gov. Paul LePage. But the party must evolve and attract more minorities, women and young people to its ranks in order to recapture the White House in 2016 and beyond, he said.
"If we want to want to have a bigger party, we have to show concern for those who aren't doing very well: the long-term unemployed ... those who live in poverty, those who live in big cities," he said.
Many saw the invitation for Paul to speak at the gathering Saturday as state party officials' effort to reach out to libertarian-leaning members, who were angered by their treatment in 2012. That year they took over the state convention and elected a majority slate of delegates for Paul's father, Ron, a former GOP congressman from Texas and presidential candidate.
Establishment Republicans challenged that decision and the national committee voted to replace half of Paul's Maine delegates with Mitt Romney supporters. Romney became the party's presidential nominee.
While tensions have cooled, hurt feelings remain among some libertarians and tea party activists who are frustrated with the party's direction.
But there is much that unites Republicans, Paul said.
"This doesn't look like division to me," to a standing ovation from the Maine GOP. "I see unity and I smell victory," Paul said.
Paul also railed against government waste and overspending, emphasized the need to gradually raise the retirement age and criticized President Barack Obama's administration for its handling of the attack on the American diplomatic compound in Benghazi, Libya.
Paul is fighting to move beyond his father's shadow and build new alliances with mainstream Republicans as he eyes a presidential bid in 2016. He said he doesn't plan to announce whether he will run until after the November midterm elections.
On Friday, he attended a private luncheon hosted by top Romney campaign advisers. He's also helped fellow Republicans across the political spectrum raise money, including on Saturday for Maine Sen. Susan Collins, who is widely considered a moderate.
Paul said that he's working with people with various views within the GOP because winning elections is done by building coalitions.
"Some people think that we need to have a litmus test on everything and we need to separate out those aren't pure enough," he told The Associated Press. "I'm the opposite: I think we need to find our common ground in the Republican Party because we believe in some common things."
Associated Press reporter Steve Peoples contributed to this report from Boston.
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