Maine Secretary of State Charlie Summers will officially launch his campaign for the U.S. Senate on Tuesday.

His attempt to win the Republican primary will start during a midday event at the Welcome Center in the Maine State House in Augusta.

Summers’ press release said he would be joined by several members of the Legislature who are backing him in the race to replace Sen. Olympia Snowe, R-Maine, who decided not to run for a fourth term this year.

The campaign release listed state Reps. Michael Thibodeau of Waldo and Amy Volk of Scarbarough as the Republican lawmakers who will attend the announcement.

Summers is one of six Republicans running in the June 12 primary for the party’s nomination. The other candidates are Attorney General William Schneider, state Treasurer Bruce Poliquin, businessman Scott D’Amboise, state Sen. Debra Plowman and former state Senate President Rick Bennett.

Four Democrats are running for their party’s nomination. They are former Secretary of State Matthew Dunlap, state Sen. Cynthia Dill, state Rep. Jon Hinck and Portland home builder Ben Pollard.

Several independents have said they are running, including former Gov. Angus King.

Independent candidates have until June to gather signatures to earn a spot on the ballot.