A win in Maine would be an important boost for Mr Paul, who is currently in fourth place
Officials in Maine are to announce the results of primary caucuses in the US state’s race for the Republican presidential nomination.
Frontrunner Mitt Romney is expected to face a tough challenge from libertarian outsider Ron Paul.
Mr Romney‘s camp is hoping a victory in Maine can help his campaign recover after conservative rival Rick Santorum won polls in three states on Tuesday.
The fourth candidate, Newt Gingrich, has not campaigned hard in Maine.
Mr Santorum has also had only limited campaign activity in the state.
The caucuses will not automatically decide which candidate receives Maine’s delegates at the Republican National Convention in August.
However, the results could still provide an important boost for the winner’s campaign.
Analysts say a loss here would be particularly damaging to Mr Romney as he previously served as governor of neighbouring Massachusetts and won the Maine caucuses easily in his failed 2008 bid for the presidential nomination.