PORTLAND – Within minutes of Democratic Rep. Tom Allen’s announcement that he’s running for the Senate, the first of several Democrats waiting in the wings to try to fill his empty seat announced he was ready to run.

Michael Brennan of Portland, former Democratic leader in the Maine Senate, said he already had filed paperwork to run for Allen’s 1st Congressional District seat. A formal announcement is planned in the weeks ahead.

Also Tuesday, state Sen. Ethan Strimling, D-Portland, announced that he was considering vying for Allen’s empty seat but that no decision had been made.

Former Maine state Sen. Chellie Pingree, who unsuccessfully challenged Susan Collins for the Senate in 2002, announced last month that she had filed with the Federal Election Commission to launch a campaign.

At least two other Democrats are considering a run: York County District Attorney Mark Lawrence and Portland lawyer Adam Cote, a former soldier who served in Iraq.

Several Republicans also are weighing bids. Those include Small Business Administration regional chief Charles Summers and Steve Abbott, chief of staff to Sen. Susan Collins, said Julie Ann O’Brien, a GOP spokeswoman in Augusta.

Other names that have surfaced include two from York County – state Sen. Jon Courtney and businessman Dean Scontras of Eliot, O’Brien said. Two others, Darlene Curley, who ran unsuccessfully against Allen in 2006, and Peter Cianchette, who lost to Democratic Gov. John Baldacci in 2002, have not ruled out a run, she said.