Attorney Mark Pera’s underdog Democratic primary campaign against Rep. Dan Lipinski in the 3rd district is gaining credibility with a handful of endorsements from reform-minded Chicago politicians.

Pera was endorsed Wednesday by Cook County Commissioner Forrest Claypool (D), who narrowly lost a 2006 primary campaign to then-Cook County Board President John Stroger (D).

The Lipinski-Pera campaign is shaping up as a battle between machine politics and reformers, as Pera seeks to cast Lipinski as a President Bush ally and machine politician who inherited the seat from his father, former Rep. Bill Lipinski (D).

“Voters are ready to turn the page on old style patronage politics,” Claypool said in a statement. “We need new, independent leaders who will serve only the public interest, not the interests of ward bosses, lobbyists and special interests. We can’t afford that game anymore.”

The well-connected Claypool could open Pera up to fundraising opportunities, as he was an early backer of now-Sen. Barack Obama (D) in 2004 and was endorsed by Chicago-area Rep. Rahm Emanuel (D) against Stroger. Claypool also previously served as Chicago Mayor Richard Daley’s (D) chief of staff, though his relationship with the mayor has since cooled.

Pera also was endorsed this week by three Democratic aldermen who won by ousting Daley-backed incumbents.

Lipinski campaign spokesman Matthew Mayer said Lipinski is focused on the energy bill pending in Congress and pointed out that none of Pera’s endorsements come from the 3rd district. “Because of his commitment to fighting for our working families on the issues of energy, the environment and health care, Congressman Lipinski has been endorsed by over 40 elected officials FROM the 3rd Congressional District,” Mayer said in a statement.

Pera outraised Lipinski in the third quarter of the year but trailed him in cash on hand, $321,000 to $180,000.

— Daniel Heim