Democratic Representative Barney Frank, who helped to craft the landmark overhaul of financial regulations that bears his name, will not seek re-election in 2012, Democratic aides said on Monday.

Frank, who has represented his Massachusetts district since 1981, will hold a 1 p.m. news conference to discuss the decision, aides said.

A close adviser told the Boston Globe that the new district in which Frank would have had to run next year was a major factor in his decision. While it retained his Newton stronghold, it was revised to encompass more conservative towns while Frank also lost New Bedford, a blue-collar city where had invested a lot of time and become a leading figure in the region’s fisheries debate.