Markus Batchelor gathers signatures for Michael Brown outside the D.C. Council swearing-in Wednesday. (Mike DeBonis/The Washington Post)

Updated 1:45 p.m. with comment from Brown.

Michael A. Brown is hoping to keep his separation from the D.C. Council brief.

Just hours before his replacement as at-large council member was sworn in, Brown went to the D.C. Board of Elections, changed his party registration from independent to Democrat and picked up ballot petitions for the April 23 at-large special election.

Brown, who lost to independent David Grosso on Nov. 6, said Wednesday he is ready to mount a “more professionalized” campaign in 2013, starting anew after his last campaign was marred by his personal foibles and the alleged theft of more than $112,000 in campaign funds.

Brown’s decision to run comes two weeks after he said in a television appearance that he was “leaning toward” pursuing a quick return to the council by running for the at-large seat vacated by now-Chairman Phil Mendelson. At the time, Brown said he had a “citywide apparatus” ready to swing into action should he decide to run.

At least three Brown volunteers were gathering signatures outside the Walter E. Washington Convention Center after the swearing-in ceremony concluded around noon. Brown said he will have about 25 workers total on the streets today, many of them veterans of Democratic presidential campaigns. They have three weeks to gather signatures from at least 3,000 city voters.

Brown narrowly survived a petition challenge last year, but he said Wednesday he’s confident he will qualify for the ballot.

“I’m really not that concerned about getting the signatures we need,” he said. “No one has an army like I have right now. … I have a citywide apparatus that is ready to go.”

What remains unclear is just how much financial and public support Brown will be able to rely on given his dismal performance in last year’s election and ongoing questions about the finances of his reelection campaign. Brown, again, is not outwardly concerned: “Folks have already started asking where they can send checks.”

Brown, son of former Democratic National Chairman Ron Brown, switched to independent status in 2008 to take advantage of the D.C. charter provision setting aside two at-large council seats for non-Democratic candidates. But Brown has continued to be active in national Democratic politics and has made no secret of his desire to switch back to the party should the opportunity arise.

“I feel back at home,” he said Wednesday.