Republicanpresidential candidate Sen. Ted Cruz of Texas signs his new book, 'A Time for Truth: Reigniting the Promise of America' for supporters in Woodstock, Georgia, USA, 03 July 2015. EPA/ERIK S. LESSER

The Export-Import Bank of the United States has been legally kaput for more than two weeks now, and Capitol Hill conservatives made clear this week that they will do whatever it takes to preserve a marquee victory -- even if it means possibly derailing a must-pass transportation bill.

Conservatives have made the demise of the Ex-Im Bank, which helps American companies by financing purchases by foreign buyers, a cornerstone of their agenda, calling it a corrupt symbol of Washington cronyism. But big-business-oriented Republicans and most Democrats want to see the bank regain the ability to issue new loans and lines of credit, warning that thousands of jobs are at risk.

[Conservatives claim big win on Export-Import Bank. But will it last?]

Sen. Ted Cruz (R-Texas) and two prominent groups of House conservatives, egged on by major activist groups, are promising to pull out all the stops to block a reauthorization -- including a Senate filibuster and possible procedural maneuvers in the House.

"I am willing to use any and all procedural tools to stop this corporate welfare, this corruption from being propagated," Cruz, a presidential candidate, said Wednesday.

Cruz has built his reputation in the Senate through his willingness to buck his own party's leaders to filibuster legislation over the federal health-care overhaul and immigration. Ex-Im, it appears, is his latest high-profile target.

The problem for Cruz & Co. is that a filibuster-proof majority of senators support renewing the bank's charter, and the necessity of extending transportation funding ahead of a July 30 deadline has given that majority a convenient vehicle for an Ex-Im renewal. Senate Majority Leader Mitch McConnell (R-Ky.) could employ hard-nosed procedural moves to block an amendment, but Democrats believe that McConnell has promised to allow a vote to attach Ex-Im to the highway bill.

Asked about that possibility, Cruz called out McConnell and House Speaker John A. Boehner (R-Ohio) by name: "They have the opportunity to deliver on their campaign rhetoric, and I am hopeful that actions will follow words."

Alternately, the Senate could take up the five-month stopgap funding bill passed Wednesday by the House without Ex-Im attached -- but, again, unless McConnell blocked amendments, the Ex-Im renewal could still be attached by senators.

[The expiration of the Export-Import Bank, explained for those who don’t know what that is]

That leaves the decisive battle for the House, where it will likely be difficult for bank foes to defeat an amendment to strip out an Ex-Im authorization from a Senate-passed bill. But Rep. Bill Flores (R-Texas), chairman of the Republican Study Committee, the largest conservative caucus, said, "we will do everything we can to continue to keep Ex-Im where it is today, and that's in wind-down mode."

Flores did not rule out urging conservatives to engage in a rare procedural maneuver -- voting against the "rule" providing for the bill's consideration on the House floor in order to block an Ex-Im renewal. Such a move is seen as a challenge to party leadership, and it could further heighten tensions between Boehner and the most conservative members of his caucus.

"I generally don't like to use taking down a rule unless it's something really significant," Flores said, promising to consult with members of his committee. "Here's the best way to look at this: Why don't we make sure it never gets to the point where there's a rule to vote on?"

Backers of the Ex-Im Bank, including the U.S. Chamber of Commerce and the National Association of Manufacturers, have been in a full-court lobbying and public-relations campaign, seeking to highlight the businesses and the jobs that could be affected by an extended lapse in Ex-Im authority.

"Every day that U.S. exporters have to compete without Ex-Im support makes it harder for them to secure the deals they need to continue growing and hiring new workers," says Exporters for Ex-Im, an advocacy group affiliated with NAM.

Wednesday's news conference outside the Capitol, featuring Cruz in perhaps the nation's most closely watched conservative lawmaker, stood as a counterpoint.

"The American people are looking for an excuse and a reason to believe in the Republican party again," said Tim Chapman of Heritage Action for America, an influential conservative activist group that has pushed to Ex-Im's demise. "We have to give them something to believe in."