AUGUSTA, Maine — Mitt Romney and Ron Paul are considered the undisputed top contenders as Maine Republican Party caucuses to choose presidential favorites get under way in earnest this weekend across the state.

The state GOP has asked local committees to caucus between Saturday and Feb. 11, and more than half of the gatherings are scheduled for this weekend. A few have already been held. Party officials plan to announce the winner of Maine’s GOP presidential sweepstakes on the evening of Feb. 11.

Maine’s presidential caucuses are essentially a straw poll and first step toward electing the state’s 24 delegates to the Republican National Convention.

In the national scheme, Maine’s caucuses are seen as more of an opportunity for momentum-building than a crucial stop for the candidates as in larger, delegate-rich states. Only one candidate, Texas congressman Paul, has made a pre-caucus visit to Maine. Romney’s wife, Ann Romney, held a fundraiser in the state in the fall. There’s little, if any, visible activity on behalf of Newt Gingrich and Rick Santorum.

Going into the caucuses, Paul’s troops are optimistic and hopeful, said Paul campaign state coordinator Paul Madore of Lewiston, who believes a well-attended series of rallies for the candidate last weekend reflect his level of support.

Other party activists credit Paul’s supporters, many of whom are young activists, for being well-organized and well-trained to participate in the caucuses.

“We’re going to continue to work really hard,” Madore said.

Romney’s list of supporters is topped by prominent state officials including Attorney General William Schneider, four state senators and seven House members, and his supporters are also optimistic about his prospects.

“Governor Romney has had a strategy and organization in the state since early on,” said Josh Tardy, a former GOP Maine House leader and supporter of the former Massachusetts governor. “Romney is hopeful for a good showing in Maine.”

Romney’s national campaign raised $24 million in the final months of 2011, far more than his competitors and leaving him with $20 million to finance his quest in state contests.

So far, Maine’s three top elected office holders are keeping mum on their choices. Sen. Susan Collins won’t endorse until after the caucuses and Sen. Olympia Snowe remains focused on her own re-election campaign and hasn’t yet endorsed anyone. Gov. Paul LePage is expected to announce his choice Feb. 11, a spokeswoman said.

Other GOP activists are being courted actively as caucuses begin.

“I’m constantly being approached,” said Debra Plowman of Hampden, the assistant Senate majority leader, who remained uncommitted going into this weekend’s Penobscot County caucuses.

Twenty-five Penobscot County municipalities are to hold their caucuses Saturday afternoon at Husson University in Bangor. The caucuses, which could draw a couple hundred people, will also be one of many caucus stops for Snowe, who will be looking to shore up support for her re-election campaign.

Aroostook County Republicans will caucus Friday and Saturday, while Cumberland County features a mix of dates between this and next weekend.

With some exceptions, Franklin, Kennebec, Lincoln, Knox, Oxford and Waldo county towns will caucus this weekend.

Maine’s Saturday caucuses share the national spotlight with Nevada. Minnesota and Colorado hold contests on Tuesday. Michigan and Arizona hold primaries on Feb. 28.