Washington ? The minimum wage increase that was supposed to zip through Congress veered onto a collision course Wednesday as lawmakers argued over business tax breaks that would be attached to ensure Republican support.

Democratic leaders in the House began laying groundwork to blame the Republicans for any impasse. Senate Democrats, however, cautioned their House colleagues not to jeopardize legislation they’d promised to approve if they gained control of Congress.

House Democrats demanded a clean bill from the Senate – no tax attachment – setting up a confrontation that could delay final congressional passage of the $2.10 per hour increase.

The Senate did vote 54-43 to advance a House-passed measure that would lift the pay floor without any accompanying tax cut. However, that was well short of the 60 votes needed to keep that version moving.

The vote was a signal to the House that without the tax breaks a minimum wage bill appeared doomed in the Senate. And the Senate promptly moved to a broader bill, backed by its Democratic leaders, that would raise the minimum wage to $7.25 per hour over 26 months and provide $8.3 billion in tax benefits to businesses over 10 years.

In the House, Democrats threatened to stifle that effort by enforcing constitutional precedents that require all tax bills to originate in the House. They blamed Republicans for the brewing impasse.

“Democrats are committed to helping small businesses, but we should not delay a minimum wage increase another day in order to negotiate a tax package,” said Brendan Daly, a spokesman for House Speaker Nancy Pelosi.

Senate Democrats seemed more willing to accept the tax portion if it meant fulfilling their campaign promise.

“Both bodies want to keep their eye on the ball,” said Sen. Max Baucus, D-Mont., a co-sponsor of the Senate tax break provisions.

House Democrats could try to alter or even remove the tax package from the Senate version when the two houses try to reconcile their differing versions in a conference committee.

In the meantime, the confrontation exposed difficulties the Democratic majority may well encounter when sending other House legislation to the Senate, where the minority Republicans enjoy more power to shape legislation than in the House.

Still, in a separate vote Wednesday, the Senate effectively killed a modified line-item veto bill. The Republican-inspired measure would have permitted the president to pluck individual items out of spending bills and submit them to Congress for a vote.

Senators also defeated a Republican amendment that would have given only the states the right to increase the minimum wage.

The federal minimum wage has been unchanged for 10 years. In the meantime, a number of states have moved on their own to increase their minimums.