Union leaders and other federal worker representatives fired back Tuesday at new Republican presidential candidate Tim Pawlenty over his call for freezing the salaries of federal workers and reducing the size of the workforce.

Pawlenty (R), a former Minnesota governor, made the comments Monday in Des Moines during the formal launch of his presidential campaign and said he would be coming to Washington this week to underscore the message about cutting federal spending.

But federal worker advocates challenged Pawlenty on his facts and said his words were based more in politics than reality.

“In targeting the federal workforce, Gov. Tim Pawlenty is following a common tact recently employed by those seeking political gain,” said Colleen Kelley, president of the National Treasury Employees Union. “However, these attacks are based more on politics than reality. Gov. Pawlenty is doing the federal workforce and the American people a great disservice by attacking federal workers and avoiding the real campaign issues.”

Dan Adcock, legislative director for the National Active and Retired Federal Employees Association, said, “We’re disappointed that in the inaugural speech of launching a presidential campaign, Mr. Pawlenty would go so far down in the weeds to be critical of the very federal employees who ensure that our food supply is safe and who found Osama bin Laden.”

NARFE does not endorse presidential candidates but plans a larger campaign “to push back on the erroneous reports about federal employees” earning too much money, Adcock said.

John Gage, president of the American Federation of Government Employees, didn’t limit his comments to Pawlenty, however, warning that it will also be difficult to motivate rank and file federal workers to support President Obama’s reelection campaign if he pursues changes to the federal pension system.

“I don’t think it’s going to be as easy to motivate our activists in 2012” to support Obama’s campaign because the White House is considering revamping the federal pension system, Gage said.

The Washington Post recently reported that White House and GOP negotiators appear to be coalescing around plans to force federal employees to pay more for their pension to help curtail the national deficit.

“A lot of our people may not be happy with the administration, especially now that they appear to be ready to touch our retirement,” Gage said. But, he added, “we’re not going to shoot ourselves in the foot and throw the Obama administration under the bus when we know we’re going to be hit by a Mack truck coming in the other direction.”

Gage was referring to Pawlenty. The former governor said his remarks will “remind the federal bureaucracy that government exists to serve its citizens, not its employees. The truth is, people getting paid by the taxpayers shouldn’t get a better deal than the taxpayers themselves.”

“That means freezing federal salaries, transitioning federal employee benefits and downsizing the federal workforce as it retires,” Pawlenty said. “It means paying public employees for results, not just seniority — from the Capitol to the classroom and everywhere in between.”

With his comments, Pawlenty reiterated his support for proposals backed by House Budget Committee Chairman Paul Ryan (R-Wis.) to extend the federal worker pay freeze to 2015, beyond Obama’s two-year freeze, and to reduce the size of the federal workforce in the coming years by replacing every three employees who leave the federal government with one new hire.

Pawlenty also appeared to endorse ideas advanced by Rep. Darrell Issa (R-Calif.), who wants a performance-based pay structure for federal workers.

Gage dismissed Pawlenty’s comments, adding that none of the GOP presidential candidates “have had anything good to say about federal employees.”

As the 2012 campaign begins, Gage said his union is earmarking at least $1 million for radio ads nationwide to promote issues of concern, including the protection of federal retirement, pay and health-care plans.

AFGE, the federal government’s largest worker union, with more than 275,000 active members, is a member of the AFL-CIO and spent more than $2 million during the 2008 presidential campaign to support Obama and Democratic congressional candidates.

Staff writer Lisa Rein contributed to this report.