WASHINGTON—Republican leaders in the U.S. House of Representatives this week purged four conservative members from key committee assignments just as talks are heating up on Capitol Hill over the approaching fiscal cliff.

Reps. Tim Huelskamp of Kansas and Justin Amash of Michigan have lost seats on the House Budget Committee while Rep. David Schweikert of Arizona and Walter Jones of North Carolina have been booted from the House Financial Services Committee. The changes will take effect when the new Congress convenes next year.

Members of the Republican House leadership would not list specific reasons for the ejections. But the ousted members and Washington-based conservative groups believe the changes were made because the lawmakers opposed too many of House Speaker John Boehner’s initiatives and deals.

“This is a clear attempt on the part of Republican leadership to punish those in Washington who vote the way they promised their constituents they would, on principle instead of mindlessly rubber-stamping trillion-dollar deficits and the bankrupting of America,” said FreedomWorks president Matt Kibbe. “This is establishment thinking, circling the wagons around yes-men and punishing anyone that dares to take a stand for good public policy.”

The shakeup comes as Speaker Boehner is trying to strike a deal with Democrats to avoid a series of year-end tax increases and spending cuts that have been dubbed “the fiscal cliff.”

All four ousted lawmakers voted against the bipartisan legislation last year that raised the federal debt ceiling and set up the conditions that have led to the fiscal cliff. Reps. Huelskamp and Amash were also the only Republican members of the House Budget Committee to oppose the budget plan authored by Rep. Paul Ryan, R-Wis. The two lawmakers believed its spending cuts did not go deep enough.

With Republican leadership now showing a willingness to consider some form of new revenue through the elimination of tax deductions and loopholes, removing lawmakers who oppose tax increases from positions on key financial committees would remove a hurdle facing the Republican establishment.

In the aftermath of losing his committee assignment, Huelskamp said he is not ashamed of what he called his principled, conservative stances.

“It is little wonder why Congress has a 16 percent approval rating,” Huelskamp said. “Americans send principled representatives to change Washington and get punished in return. The GOP leadership might think they have silenced conservatives, but removing me and others from key committees only confirms our conservative convictions. This is clearly a vindictive move, and a sure sign that the GOP establishment cannot handle disagreement.”

While Amash, Schweikert, and Huelskamp were first elected in 2010 with the backing of the Tea Party, Rep. Jones is about to begin his 10th term in Congress.

“I’m not going to sacrifice my integrity for anyone or any party,” Jones said. “It’s the price you pay. I didn’t come up here to be a puppet for anyone. And I think the public back in my district, which is the most important, has seen I’m willing to do what I think is right.”

The reassignments were not the only signs of a growing wedge between the Republican leadership and the conservative movement.

Top congressional Republicans released their proposal to avoid the fiscal cliff on Monday, and conservative lawmakers and organizations quickly bashed the $2.2 trillion GOP plan that would close tax loopholes and cap deductions while making minimal changes to entitlement programs.

Sen. Jim DeMint, R-S.C., warned that Boehner’s plan would “destroy American jobs and allow politicians in Washington to spend even more, while not reducing our $16 trillion debt by a single penny.”

“This isn’t rocket science,” Sen. DeMint continued in a statement. “Everyone knows that when you take money out of the economy, it destroys jobs, and everyone knows that when you give politicians more money, they spend it.”

Meanwhile, The Heritage Foundation went further in attacking the letter containing the proposal that the Republican leadership sent to the White House.

“Rarely in modern American politics have more counterproductive, more foolish words been set to paper,” wrote The Heritage Foundation’s Alison Acosta Fraser and J.D. Foster. “The Republican counteroffer, to the extent it can be interpreted from the hazy details now available, is a dud. It is utterly unacceptable. It is bad policy, bad economics, and, if we may say so, highly questionable as a negotiating tactic.”

The piling on continued in an open letter signed by more than 100 conservative activists, including the Leadership Institute’s Morton Blackwell, Eagle Forum founder Phyllis Schlafly, Family Research Council Action’s Tom McClusky, American Values president Gary Bauer, Concerned Women for America CEO Penny Nance, and American Conservative Union Chairman Al Cardenas.