A House committee took a step Thursday toward keeping highway and transit aid flowing to states just three weeks before transportation programs are forecast to go broke.

The Ways and Means Committee approved by a voice vote a bill by its chairman, Rep. Dave Camp, R-Mich., that cobbles together $11 billion in pension tax changes, customs fees and money from a fund to repair leaking underground fuel storage tanks to shore up the federal Highway Trust Fund through May 2015.

Transportation Secretary Anthony Foxx has warned that by the first week in August the fund will no longer have enough money to cover promised aid to states, and the government will begin slowing down payments. The fund is forecast to reach a zero balance by the end of August.

Democrats oppose the Camp plan, saying it allows Congress to put off finding a long-term solution to the chronic money shortage that has kept transportation aid teetering on the edge of insolvency since 2008.

An amendment by Rep. Earl Blumenauer, D-Ore., that would have committed Congress to passing a six-year transportation bill before the end of this year was defeated along party lines.

"It is a mistake to take the pressure off this Congress and kick it down the road," Blumenauer said. Congress will likely have more difficulty reaching an agreement on a long-term plan next year in the partisan atmosphere of a presidential campaign, he said.

But Republicans said more time is needed to reach a long-term solution. Camp said he wanted to fund the program through the end of 2015 to buy more time to work on a longer-term bill but couldn't find enough money in tax increases or spending cuts to do that.

"A funding package that just goes to the end of 2014 would only create a larger crisis in December," he said.

House Speaker John Boehner, R-Ohio, told reporters he intends to bring the bill up for a vote in the House next week. It's not clear, however, whether Boehner has enough votes to pass the measure without Democratic support. Some GOP conservatives oppose transferring money from the general treasury to transportation programs, saying they want to limit highway and transit spending to money raised by federal gasoline and diesel taxes. The fuel taxes are the Highway Trust Fund's main revenue source, but they haven't been raised in 21 years and aren't keeping pace with spending.

Even if the GOP plan passes the House, it could run into trouble with Senate Democrats.