Mr. Altmire joined other Allegheny and Beaver county Democratic officials to close ranks around Mr. Critz after the intraparty feud and focus on the general election campaign against Republican Keith Rothfus, an Edgeworth attorney.
Southwestern Pennsylvania had five Democratic congressman in 2000 but would be down to one (Mike Doyle of Forest Hills) if Rothfus won, Mr. Altmire warned.
"That cannot be allowed to happen," he said at a rally at the Allegheny County Courthouse. "And it's no coincidence that when you go back 12 years -- that was about the time when that change started to occur here -- that it also started to change for the country, and we started to implement policies that would send this economy into the tailspin that we nearly collapsed from in 2008."
Mr. Doyle sounded the same theme, echoing criticisms of the George W. Bush administration. "I have a message for Mitt Romney and Keith Rothfus. We're not going to let you return to the policies that almost bankrupted this country," he said.
Mr. Rothfus enjoys a financial edge over Mr. Critz, who was forced to spend much of his campaign funds in his underdog battle against Mr. Altmire. The Republican should also be well-known in the suburbs north of Pittsburgh from his own run against Altmire in 2010, in which he lost by less than 2 percentage points. National Republicans are already running advertisements against the incumbent Democrat, saying he has repeatedly voted with the Obama administration's wishes on health care reform and other issues.
Republican mapmakers pushed the 4th and 12th districts together during decennial redistricting last year. The northern suburbs make up the bulk of the combined district are new to Critz, which is one reason why his campaign gathered Mr. Altmire and other Allegheny and Beaver county officials around him today.
Mr. Critz said Mr. Altmire "deserves all of our support and all of our respect" for endorsing him, and signaled through the fall that he will continue warning against Republican changes to Social Security and Medicare, as he has in past campaigns, and hammering blue collar issues.
"It's about middle America. It's about working men and women. It's about working families and making sure we're supporting policies giving everyone a chance to move forward, to succeed in this country," Mr. Critz said.
Critz is a former aide to late U.S. Rep. John Murtha of Johnstown, who was one of the five local Democrats in Congress in 2000 referred to by Mr. Altmire. The others were Doyle, Bill Coyne, Ron Klink and Frank Mascara.
UPDATE: Full statement from Rothfus camp below:
"It is no surprise that Congressman Jason Altmire has endorsed fellow Democrat Mark Critz in PA's 12th Congressional District. They both, after all, voted to keep the Medicare-destroying and budget-busting Obamacare bill in place. And they both share President Obama's indifference to the five trillion dollars in debt the President has rung up over the last three and a half years and the additional $6.4 trillion the President would add to the nation's debt over the next ten years.
Congressman Altmire and Critz both believe the answers to our problems must come from Washington and not the people of Pennsylvania. They believe a few people in our nation’s capital have the power to tell us everything from what kind of light bulb to use in our home to what is- and is not- allowed to be in our health plans. This liberal vision, shared with President Obama, is one of a government-centered society. With 38 months of higher than 8% unemployment, that vision has failed the hardworking people of Southwestern PA. I look forward to a robust debate with Congressman Critz regarding the steps we need to take to re-light the American economy, the American spirit, and the American Dream."