Joe Kennedy won’t challenge Sen. Scott Brown in 2012

Massachusetts is losing one of its House seats thanks to redistricting, which means one of the Democrats in the all-Dem House delegation will have to retire, run for an alternative office or challenge a fellow House member.

Obama, meanwhile, was in Boston Tuesday to discuss innovative education strategies.

He also hosted a fundraiser Tuesday evening at the Museum of Fine Arts for the Democratic Congressional Campaign Committee. At that fundraiser, according to the White House pool report, was Vicki Kennedy — the widow of the late Sen. Kennedy, who was urged to run for his seat. She told the Boston Globe earlier this year she would not run for the Senate in 2012, but she campaigned for Democratic nominee Martha Coakley in the special election and is likely to campaign for the 2012 nominee.

Also at the fundraiser was Rep. Ed Markey (D-Mass.), who’s another potential Senate candidate.

Brown has held a steady lead against potential Democratic challengers in polling on the race. But most organizations rate the race a toss-up, given Massachusetts’ blue state status and because Obama will top the ticket in 2012.