WASHINGTON - A nagging $8 million slice of the $690 million St. Croix River bridge project is giving opponents fresh ammunition to try to derail the proposal in Congress.

They're calling it an earmark, a word that riles emotions in a time when Republicans and Democrats are trying to wring savings from the federal budget. Even though bridge supporters disagree with that definition, they acknowledge a problem -- having to find the same amount elsewhere to "offset" the designated money.

The alleged earmark came to light recently when the Congressional Budget Office (CBO) said a bridge bill introduced by U.S. Rep. Michele Bachmann would lead to $8 million in direct federal spending. Former U.S. Rep. Jim Oberstar said the CBO's score complicates things in Congress.

"Finding an $8 million offset in this very tight budget structure is going to be difficult," said Oberstar, former chairman of the House Transportation Committee.

Bachmann's bill seeks an exemption to a law that protects the St. Croix and 202 other scenic rivers nationwide, without which the bridge cannot be built.

The earmark question presents a sticky political dilemma for Bachmann, who is campaigning for the presidency and opposes earmarks. Bachmann, chief sponsor of a House bill that would permit construction of a four-lane bridge at Oak Park Heights, denies that the contested money is an earmark.

The $8 million consists of "authorizations that were made into law two years before I was even a member of Congress," the Minnesota Republican said. "We are currently working with the committee of jurisdiction to ensure this legislation is offset. Make no mistake; it will be offset."

Any House bill that increases federal spending must offset the spending with equivalent cuts.

Two Twin Cities Democrats in Congress, U.S. Reps. Betty McCollum and Keith Ellison, have seized on the earmark question, urging colleagues to keep Bachmann's bill off the House suspension calendar -- a fast track for passage without debate.

"This bill requires the construction of an exotic $700 million 'extradosed' bridge design, designates a specific location, and comes with a CBO-scored price tag which makes H.R. 850 the equivalent of a congressional earmark," the letter said.

An old earmark

The $8 million stems from money that was in fact earmarked -- but in 2005, before Bachmann was in Congress. The money, earmarked by then-Sixth District Rep. Mark Kennedy and then-U.S. Sen. Norm Coleman in a $286 billion federal transportation bill, allocated $13.4 million for preliminary design studies and land acquisition in Oak Park Heights.

"If we thought about politics as normal this wouldn't be a really big deal, but it's about Michele Bachmann," Mayor David Beaudet said. "She's the one that made this a big political issue. Even if she finds an offset, it's still an earmark and a lot of those Tea Party people don't want to vote for earmarks."

The Minnesota Department of Transportation (MnDOT) has spent $4 million of $12 million it received from the earmark, according to congressional sources. The larger share of the bridge's cost comes from state and federal money already set aside in Minnesota and Wisconsin.

Erich Zimmermann, a senior policy analyst at Taxpayers for Common Sense, said his organization opposes the bridge because it's too large and wasteful. But he isn't labeling the $8 million an earmark outright.

"It exists in a gray area," Zimmermann said. "It's sort of an earmark enabler. It's allowing earmarked money to be spent."

U.S. Rep. Rob Bishop, R-Utah, chairman of the House National Parks, Forests and Public Lands Subcommittee, said he disagreed with the CBO's assessment. Cuts that fall within the subcommittee's jurisdiction will have to offset the $8 million, said Bishop, who voted for Bachmann's bill.

U.S. Sen. Amy Klobuchar, D-Minn., has introduced a companion bridge bill in the Senate.

Delays in congressional action could hurt the current push for the long-debated bridge.

A deadline imposed by Gov. Mark Dayton to resolve the issue in Congress no longer exists, said Kevin Gutknecht, a MnDOT spokesman. "We still have some time to play with, and we want to do everything we can to help our congressional delegation with this effort."

McCollum has long said she supports a new St. Croix River bridge but not the current proposal, which she considers excessive in size and cost. She now has an ally in Ellison.

"A smaller bridge ... would be much more careful use of the public dollar," Ellison said.

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