AUGUSTA — Republicans who live in Senate District 21 will meet tonight at the Augusta Civic Center to choose a new candidate.

The caucus is set for 6 p.m. in the Kennebec/Penobscot Room at the civic center. Voter check-in begins at 5 p.m.

The location has been changed from the Manchester Fire Station because the crowd is expected to be in the hundreds, said Mark Ellis, spokesman for the Kennebec County GOP Committee.

Rep. Patrick Flood, R-Winthrop is running against West Gardiner businessman Ryan Wheaton for the nomination. Flood, House chairman of the Appropriations Committee, jumped in the race after Sen. Earle McCormick, R-West Gardiner, announced he would not seek re-election.

On Sunday, House Speaker Robert Nutting, R-Oakland, issued a statement in support of Flood.

“Pat Flood has been an extraordinary leader in the Maine Legislature and has served the people of his House district very well,” Nutting wrote. “He has led our state through difficult budgetary times and oversaw the largest tax cut in Maine history.”

Wheaton joined the race shortly after Flood announced his intention to run. Wheaton said he wanted to offer district voters a more conservative choice. The Christian Civic League of Maine has encouraged supporters to go to the caucus to vote for Wheaton.

“We urge you to support Ryan Wheaton, a Christian businessman at the Republican Caucus District 21 race,” wrote Civic League Executive Director Carroll Conley.

In 2009, Flood voted in support of same-sex marriage while a member of the House. Wheaton said he opposes gay marriage.

The caucus winner will face Democrat David Bustin of Hallowell in November.

Senate District 21 includes Chelsea, Farmingdale, Gardiner, Hallowell, Litchfield, Manchester, Monmouth, Pittston, Randolph, West Gardiner and Winthrop.