With a budget showdown looming, Republican Senate leaders turned up the heat Tuesday on President Obama, pinning responsibility on the White House to propose cuts in entitlement spending and saying Obama would have to “bite the bullet” to keep the national debt under control.

“There will be no entitlement reform without presidential leadership,” said Senate Minority Leader Mitch McConnell.

McConnell said Republicans would listen to proposed cuts from the president, but would refuse to compromise on raising taxes.

Tennessee Republican Sen. Lamar Alexander echoed McConnell, putting the responsibility for spending cuts on the White House, not Congress.

“We need to deal with the entire budget, and we can’t do that unless the president himself says, ‘All right, I’m ready to bite the bullet, and I need some of you to go with me,’ and some of us are,” Alexander told reporters. “In fact, there’s a lot of us [that] are. A Congress of 535 people can’t speak with a single voice. The president can.”

Congress has less than a month to reach an agreement on how to fund the government beyond March 4, when the latest temporary funding measure expires.

The continuing resolution, which is currently keeping the government operational, is a stopgap measure to fund government operations until Congress reaches a budget resolution. Legislators from both parties have expressed concern over a potential government shutdown if Congress cannot agree upon a funding measure before then.

McConnell accused Democrats of trying to scapegoat Republicans by bringing up the possibility of a shutdown. He said the resolution, along with Obama’s request to raise the debt ceiling, provided “opportunities to do something important on spending and debt.”

Alexander pointed to the nation’s trillion-dollar deficit, saying, “you don’t have to get very far beyond third grade math to know that our country’s headed for trouble unless we reduce spending.” He said Obama’s State of the Union address lacked a sense of urgency over the debt, but the real test would be when the president releases his budget next week.

Among the entitlement programs up for cuts, Alexander said that Social Security was a “good place to start.”

“The era of Social Security surpluses is over,” Alexander said. “It’s very significant that this year Social Security has more money going out than coming in, and it’s very significant that in the next ten years Social Security will add a half trillion dollars to the deficit. Social Security would be a good place to start when dealing with these mandatory entitlement programs that are 57 percent of our budget.”