Norquist, the president of Americans for Tax Reform, is known for his Taxpayer Protection Pledge against raising taxes, which has been signed by nearly all Republican lawmakers. Democrats have argued that the pledge ends any conversation about compromising on a balanced budget.

Senate Democrats have tried to portray Republicans as beholden to special interests such as Norquist and the Tea Party.

Senate Majority Leader Harry ReidHarry Mason ReidGOP poised to advance rules change to speed up Trump nominees Dems walk tightrope on Pompeo nomination The Memo: Teens rankle the right with gun activism MORE (D-Nev.) on Tuesday called Norquist the de facto head of the party and said that GOP lawmakers were "being led like puppets" by him.

“They’re giving speeches that we should compromise on our deficit. Never do they compromise on Grover Norquist. He is their leader,” Reid said.

McCaskill on Thursday said both parties needed to make a greater effort to compromise.

“I don’t get this, I don’t get how. We have to be able to compromise on all of these things,” McCaskill said. “We have to compromise on entitlements, we have to compromise on revenue, we have to compromise, compromise, compromise, and quit worrying about winning elections, because if you compromise with someone, then you are tacitly admitting that you can work with them. Both parties are so anxious to prove that the other party is unreasonable.”

Republicans countered that when they have compromised on tax increases for budget cuts in the past, the federal government continued to ramp up spending despite the agreement.

McCaskill said that this time is different.

“I know how much Missourians want to cut spending,” she said. “This is now politically important. If you talk to anyone who’s been polling in this country for the last two years, there is a huge sentiment out among the people that I work for — they don’t understand why everywhere they look people are cutting back. The city council is cutting back, the school board is cutting back, the state government is cutting back, and meanwhile [the federal government] is not. So I think there’s a real political push now to make good on the spending cuts that will hold people accountable.”