BANGOR — Sen. Rand Paul faces a divided Republican Party as he arrives in Maine.

The Kentucky Republican is set to address the state Republican convention on Saturday, an annual event for GOP officials troubled by infighting since libertarian-minded activists loyal to Paul’s father seized control of the state party. This year’s theme is “unity,” an optimistic note from party officials in Maine and Washington who suggest that things have improved in recent months.

But Paul’s White House ambitions — and Maine’s Republican Gov. Paul LePage’s re-election prospects — may depend on whether the freshman U.S. senator can help mend divisions between his party’s establishment and tea party wings as he eyes a presidential run in 2016.

No state showcases Paul’s challenge more than Maine.

He hopes to promote further party unity ahead of the November re-election test for LePage, considered one of most endangered Republican governors in the nation. At the same time, Paul is pushing to strengthen his appeal beyond his father’s passionate supporters to prove he can be a credible national candidate. He has yet to announce his 2016 intentions, but says he is seriously considering a run for president.

“The Republican Party will adapt, evolve or die,” Paul declared in a speech at Harvard University’s Institute of Politics on Friday as he worked to build new alliances with mainstream Republicans in Boston.

Before the speech, the freshman senator attended a private luncheon hosted by top lieutenants of former presidential nominee Mitt Romney. Romney’s former national finance chairman Spencer Zwick arranged a private audience of just a dozen key members of Romney’s inner circle.

“This was meant to be a real discussion with people that I view can be very helpful,” Zwick told The Associated Press, adding that Paul “was very well received” during an hour-and-a-half discussion about policy and politics over salad and fresh fruit.

Paul’s Maine audience will be larger and more rowdy.

After two tumultuous conventions that revealed cracks in the Maine GOP, party leaders are trying to build a strong, unified base that will shepherd in four more years for LePage, who rode tea party support to victory in 2010.

Many view Paul’s invitation as the party’s attempt to reach out to libertarian-leaning members, who remain wounded by their treatment in 2012 after they took over the state convention and elected a majority slate of delegates for Paul’s father, former Rep. Ron Paul, R-Texas. Establishment Republicans challenged that decision and the national committee voted to replace half of Maine’s delegates for Paul with Romney supporters.

Several Paul supporters quit the party in frustration. Among the rest, tensions have cooled, but hurt feelings remain — and will even after the senator from Kentucky’s speech.

“Paul is going to leave Maine and what happens within the party is still going to be there,” said Vic Berardelli, chair of the Maine Republican Liberty Caucus, which includes many Paul supporters.

But Paul also provides an opportunity to bridge the gaps between the different factions with a message that appeals more broadly than his father’s, members of the party say.

Over the last year, Paul has stood alongside Republican National Committee Chairman Reince Priebus in places like New Hampshire and Michigan as the national party works to mend internal divisions and strengthen its appeal among young people and minorities. Paul has helped fellow Republicans across the political spectrum raise money, as he is expected to do Saturday for Maine Sen. Susan Collins, who is widely considered a moderate.