Now that the moment congressional Republicans have been waiting for has arrived — the near-certainty that they can finally repeal the Affordable Care Act — some conservative lawmakers and groups are worried their GOP colleagues are losing their nerve.

"Suddenly, after six years of calling for full repeal of Obamacare, Washington politics are getting involved and we are headed for a worse deal than we had agreed to when we sent a reconciliation bill to President Obama's desk," an aide to an influential member explained, referring to the repeal bill Obama vetoed in late 2015.

"Some Republicans seem to want to put something less on Mr. Trump's desk than they sent to Obama. There's discussion of keeping certain taxes, some of the mandates and regulations, and setting up a reserve fund.

"There's talk of an 'off-ramp' being three to four years long," the aide continued. "How can we face constituents next election cycle and tell them that we still haven't fully repealed Obamacare?"

On the record, members admit they are pressing leadership for quick action — and a detailed plan — so they can show voters that Republicans deliver on their promises.

Members want as much "specificity" about the replacement plan as possible ahead of Friday's scheduled House vote on a budget resolution, "so that we can go back to our constituents and say, 'Here's what we voted for; here's what we passed; here's what we're hoping to get passed in the Senate, and that way it gives a little more certainty," said Rep. Mark Meadows, R-N.C.

Republican Study Committee Chairman Mark Walker "knows repealing Obamacare quickly is key to gaining back the trust and confidence of the American people," the North Carolinian's spokesman said.

"We've had almost seven years to come up with an alternative and the fact that we don't [have a bill moving] is unacceptable," said Jason Pye, spokesman for the libertarian advocacy group Freedom Works. "They can't be afraid," to fully repeal and replace the Affordable Care Act, he said about Congress.

"I think Republicans have said for long enough that they are going to repeal Obamacare … that they have to have something to show for it," Pye continued. "You have to have a full, complete plan within a two-year window. I think politically they have to do it. They can't afford to punt on this, just from an electoral point of view," he said about the possibility of Republicans entering the mid-term elections with the job incomplete.

"Too often, Washington puts the concerns of the politically connected before those of ordinary Americans," House Freedom Caucus Chairman Meadows and past chairman Rep. Jim Jordan, R-Ohio, wrote in an opinion-editorial for The Hill titled "no more excuses" Wednesday.

"Republicans have an incredible opportunity in front of them, but also a tremendous responsibility," they continued. "Our task is simple: do what the voters sent us to do."

Fully repealing and replacing the ACA tops Meadows' and Jordan's "to-do" list.

"And don't take three years to do it," they instructed.

President-elect Trump pledged quick action Wednesday.

"We're going to be submitting as soon as our secretary is approved, almost simultaneously, shortly thereafter, a plan," Trump promised during a news conference."It will be repeal and replace. It will be various segments, you understand, but will most likely be on the same day or the same week, but probably the same day. Could be the same hour."

His willingness to take the lead could tip the scale toward action, said Rep. Chris Collins, R-N.Y., his unofficial congressional liaison.

"Our new secretary of HHS has had a plan in his pocket now for the last three years," Collins told reporters Wednesday, referring to Trump's nominee to lead Health and Human Services, Rep. Tom Price, R-Ga.

"If they did present an actual specific plan, that would be a much easier starting point than taking six plans or no plan and trying to start with that," he said. "I think that would speed the process up incredibly."