WASHINGTON - Mark Rosenker, the face of the federal government's Interstate 35W bridge investigation, kept his distance Wednesday from the political firestorm ignited by his agency's controversial findings on the bridge collapse.

"My job is to call it like it is," said the chairman of the National Transportation Safety Board (NTSB), who tied the Aug. 1 catastrophe not to corrosion and improper maintenance, but to a design failure in the bridge's original construction. "We deal in facts, analysis and science. Politics, in any way, shape or form, does not enter into the decisions we make."

Rosenker, 61, brought a lifetime of experience in the military, electronics, communications and politics when President Bush appointed him to the safety board in 2003. By then, he had worked on most of the Republican presidential campaigns since Richard Nixon's 1972 reelection.

When he was sworn in as board chairman in 2006, Vice President Dick Cheney credited him with overseeing some of "those secure, undisclosed locations where I've been known to spend some of my time."

While he's no stranger to politics, Rosenker, a retired Major General in the Air Force Reserve, forcefully disavows any part in bridge politics. The debate has pitted Republican Gov. Tim Pawlenty against Democrats critical of what they see as his administration's inadequate investment in maintenance and inspections.

"I don't know what the debate is, or what people are alleging," Rosenker said in an interview with the Star Tribune.

What some Minnesota Democrats -- particularly Rep. Jim Oberstar, chairman of the U.S. House Transportation Committee -- have alleged is that Rosenker overstepped his mandate Tuesday by ruling out the role of rust and corrosion while announcing a preliminary finding of a design flaw in the bridge.

Oberstar called it "an inappropriate, unfortunate and uncharacteristic statement by a board chairman," though the congressman stopped short of ascribing an explicit political motive to Rosenker.

Rosenker, whose agency is widely praised by experts in transportation safety, says the NTSB's conclusions are strictly fact-based.

"There may be swirls of politics around the issues that we deal in, but we do not take any political sides," he said.

While the final cause of the bridge failure still might not be known until next fall, Rosenker said, the NTSB investigation has surmised so far that it originated with a failure of 16 gusset plates that were sized a half-inch too thin in the original 1960s design.

Rust, corrosion, and the state inspections that seek to discover and remedy such problems had little to do with the collapse, according to Rosenker.

"What broke was the U-10 [a node of gusset plates that connect the bridge's beams]," he said. "We know why it broke: because it was inadequately designed for this bridge."

Might rust and corrosion prove later to have been contributing factors, as has been alleged by critics of the Minnesota Department of Transportation?

"We did not believe it played much of a role in any way on this issue," Rosenker replied. "It was a weight-bearing issue."

Politics at the periphery

To Rosenker, who has deep ties to the Bush administration and the Republican Party, politics is a bit like the rust on the I-35W bridge: It's there, but not something he thinks should be taken into account.

"It's not like we've never seen politics in the periphery of what we do, but it has never affected what we do," he said.

Politics have long been a little more than peripheral in Rosenker's career. Before his appointment to the NTSB, he worked as Deputy Assistant to the President and Director of the White House Military Office. That's where he worked closely with Cheney.

Alongside his 37 years in reserve and active duty the Air Force, Rosenker spent 23 years lobbying for the Electronic Industries Alliance.

His work in the electronics sector nurtured a close friendship with Rep. Darrell Issa, R-Calif., who spearhead the recall of former California governor Gray Davis, paving the way for the election of Republican Arnold Schwarzenegger.

Rosenker credits his experience in the electronics industry with giving him the technological background he needs at the NTSB.

His transportation credentials come from his background doing public relations for a national firm that represented the American Safety Belt Council, the Motorcycle Safety Foundation, and the Safety Helmet Council of America. But Rosenker's ascendancy to NTSB chairman is generally seen as a reflection of his political and communications know-how more than his technological acumen.

Unanimous decision

Jeff Davis, editor of the independent Transportation Weekly, which analyzes federal transportation policy, notes that the five-member NTSB board is by law composed of at least three people with technical qualifications, and others with the savvy to deal with politicians and the press.

Rosenker, as chairman, is the NTSB's primary spokesman.

"He does not have a partisan reputation that I know of," Davis said. "More significantly, in regard to I-35W, was that the report issued yesterday was the unanimous recommendation of all five board members."

That means that it had the imprimatur of the NTSB's technical staff, which is highly regarded in transportation circles.

"The NTSB is a group that is considered separate and not political," said Greg Cohen, president of the American Highway Users Alliance, which promotes road safety. "They are basically seen as a group of dedicated engineers, shielded from politics."

Rosenker, reflecting on his agency's role, said its credibility is its only stock in trade. "That's all we have at the NTSB. ... We only have our reputation as a body of investigators that do their job thoroughly."

Kevin Diaz • 202-408-2753