By Patricia Zengerle
WASHINGTON (Reuters) - The Republican takeover of the U.S. Senate will bring a tough new tone to the debate over Washington's foreign policy, with lawmakers expected use their new clout and power over the budget to promote a more interventionist foreign policy.
While leaders of the Democratic-majority Senate mostly backed President Barack Obama's international goals, Republicans plan to pressure the White House to take a tougher line on Iran, Russia and Islamic State fighters in Iraq and Syria.
"I think the Congress can and will be heard from, particularly on the funding side," John Thune, a member of the Senate's Republican leadership, said in a telephone interview.
After Republicans, who already controlled the House of Representatives, won a majority in the Senate on Tuesday, two of Washington's most vocal foreign policy hawks, John McCain and Lindsey Graham, came in line to chair two key Senate panels.
McCain, who has advocated a more robust response in both Ukraine and Syria, will lead the Senate Armed Services Committee, which oversees military policy. That includes a say in the budget, giving him a strong lever on policy.
Graham is due to chair the Senate appropriations subcommittee that controls the State Department's budget and can withhold or grant aid to foreign governments.
Tennessee Senator Bob Corker, in line to be chairman of the Senate Foreign Relations Committee, is known as a consensus-builder. But he has backed a sterner policy for Syria and lamented what he sees as a lack of communication with lawmakers by the Democratic White House, which could mean more hearings.
The Foreign Relations committee has the power to approve or reject Obama's nominees for ambassadorships and top State Department positions before they face a full Senate vote.
IRAN DEADLINE LOOMS
The Senate's power shift also could have a big influence on deals the administration reaches with other countries.
An early opportunity for the Republicans to flex their new muscle will come with the agreement that Obama is trying to negotiate with Iran by Nov. 24 to curb its nuclear program.
To reach a deal, Obama must be able to convince Tehran that Washington will lift sanctions. Republicans, who worry that Obama will make too many concessions, are talking about turning the screw on Tehran and imposing yet more sanctions.
Democrats and Republicans are at odds about when to vote on a new authorization Obama wants for his campaign against Islamic State. Democrats want a vote before they hand over power in January, while Republicans want to delay until then.
While Obama and other Democrats want a ban on U.S. ground troops in the conflict, many leading Republicans insist that all options should be open.
The new Congress is expected to take a tougher line against Russian President Vladimir Putin over Ukraine, including pushing for more sanctions. Some Republicans favor sending U.S. weapons to Kiev, a move Obama as well as most NATO allies reject.
There are limits on how assertive the new Congress will be, as the Republican Party also includes members who want less foreign involvement, including a likely 2016 presidential contender Senator Rand Paul.
"It's going to be interesting to see if the Republican tone differs now that they have the responsibility to govern rather than just criticize," said Democratic Senator Christopher Murphy, a Senate Foreign Relations Committee member.
(Additional reporting by David Lawder; Editing by David Storey, Jonathan Oatis and Lisa Shumaker)