Senate Republicans on Tuesday blocked consideration of an amendment to the Wall Street reform bill that would curb high-risk trading by big banks. The move potentially put the entire financial measure in jeopardy.

Sen. Carl Levin (D-Mich.), co-sponsor of the amendment, said that the decision by Republicans to block the amendment could keep him from voting to end debate on Wednesday.

“I’m not inclined to vote for cloture if I can’t get a vote” on my amendment, Levin said of the amendment he co-sponsored with Sen. Jeff Merkley (D-Ore.).

Merkley declined to say whether he would vote for cloture, saying he was putting the responsibility “squarely on Republicans, where it belongs.”

The pair blasted Senate Republicans at a press briefing for not allowing the process to move forward.

Senate Banking ranking member Richard Shelby (R-Ala.) objected Tuesday afternoon on behalf of others to allow debate on the amendment.

“Republican leadership is obviously carrying Wall Street’s water,” Levin said, calling the amendment a key reform to the financial regulatory reform overhaul. “The stakes here are huge in terms of conflict of interest.”

In addition to limiting proprietary trading, the amendment would also require nonbank financial institutions to shore up their capital reserves.

Banking Chairman Chris Dodd (D-Conn.) and the Treasury Department both support the measure.

The Senate is poised to end debate Wednesday on the measure, which has been on the floor for more than three weeks.

Majority Leader Harry Reid (D-Nev.) predicted Tuesday that “a number of Senators, Republican Senators, have told me they will vote for cloture.” However, Reid will have to keep his Democrats in line. Sen. Byron Dorgan (D-N.D.) has maintained he will not vote for cloture if he thinks debate is being cut off too soon.

Jessica Brady contributed to this report.