A Senate panel is expected to vote next week on arming vetted Syrian rebel groups.

The vote by the Senate Foreign Relations Committee would mark the first time lawmakers have voted to approve arming Syrian rebels and could increase pressure on the Obama administration to take action in the 26-month-old civil war. 

{mosads}The top Democrat and Republican on the Senate Foreign Relations panel announced they had introduced the Syria Transition Support Act on Wednesday. A vote on the bill is expected as early as Tuesday afternoon.

Panel Chairman Robert Menendez (D-N.J.) agreed to modify the bill he introduced last week in order to get ranking member Bob Corker (R-Tenn.) on board. Such bipartisan action would send the strongest signal yet to the Obama administration that Congress is demanding stronger action while giving a boost to similar legislation that Rep. Eliot Engel (D-N.Y.), the top Democrat on the equivalent House panel, introduced in March.

“It’s largely along the line of what I originally introduced,” Menendez told The Hill in a hallway interview, “but with a little bit of expansion, and we’re together on it now, and we’ve refined all the language.”

The bill would create a $250 million a year transition fund to assist the civilian opposition and sanction sales of weapons and oil to the regime of Syrian President Bashar Assad.

“The future for Syria is uncertain, but the U.S. has a vested interest in trying to prevent an extremist takeover, which poses a very real risk for us and the region,” Corker said in a statement announcing his co-sponsorship. 

“Without authorizing the use of force or additional spending, this legislation will begin to implement a more coherent U.S. strategy, both now and for the day after Assad, that is focused on trying to shift the momentum on the ground toward moderate opposition groups while also helping them build support within and outside Syria for a new government,” he said.

The White House has balked at arming the rebels, saying U.S. weapons would add to the violence that has already killed almost 100,000 people. It also argues weapons could end up in the hands of Islamist militants opposed to the United States. Administration officials have said they are reconsidering their reservations in the wake of reports that Assad’s regime may have used chemical weapons.

The bill comes as Secretary of State John Kerry announced last week that the United States and Russia are collaborating on a last-ditch peace conference between the Syrian government and the opposition. The conference is expected to take place under the auspices of the United Nations, Kerry said Tuesday, probably in early June.

Lawmakers welcomed the diplomatic effort but made it clear they want to see more action if it fails.

“I’m hopeful because anything that can create a political solution to the crisis is desirable,” Menendez told The Hill on Tuesday. “Having said that, I still think we have to create a parallel track to help the rebels should, in fact, the political solution not materialize.”

Jordy Yager contributed

This story was updated at 1:11 p.m.