Republicans had 6-8 years for a plan. Why haven't they come up with a replacement yet?
They did. There are at least three (Rand Paul says "about fifty"). Note that Tom Price (nominee for Health and Human Services, the department that oversees the PPACA system) is known for writing one.
- Tom Price
- Phil Roe
- Paul Ryan
All three of these are actual bill proposals from the most recent Congressional term. Apparently there is also some chatter about reviving the old Bob Dole plan of offering everyone the same choices available to federal government employees. Obviously that wouldn't be a current bill although there might have been one in 1996.
It's worth noting that most new coverage under the Patient Protection & Affordable Care Act (PPACA; popularly called Obamacare) is based on Medicaid, not the exchanges (example source). While the exchanges have twelve million enrollees, some of those were covered before and switched either voluntarily or as a result of plan loss.
Beyond that, most of the Medicaid effect was what is called "woodwork effects" meaning that people previously eligible signed up because they, well, asked. In other words, most of those who signed up for Medicaid were eligible for Medicaid prior to PPACA but didn't enroll until after it was passed. These people would still retain coverage after PPACA repeal even without a replacement.
Similarly, many Obamacare exchanges are state programs. While a Republican Obamacare replacement may remove the subsidies to those plans, it wouldn't be able to remove state-run exchanges even if it wanted to do so. Remember that there were seven Supreme Court votes against unfettered federal oversight in the Medicaid expansion portion of PPACA. One of those votes was Antonin Scalia, but even if his replacement ruled differently, that's still a six vote majority against federal interference. So they may lose subsidies, but people who want to buy plans on exchanges would still be able to do so.
why are Republican law makers so eager to repeal it without a backup plan?
Repeal can be done in reconciliation, which only requires a simple majority in the Senate. Republicans have a simple majority in the Senate, so they can repeal it.
Passing a replacement that does more than fiddle with budget numbers requires a sixty vote supermajority in the Senate under current law. Republicans, unlike 2009 Democrats, do not have a sixty vote supermajority (fifty-two Republicans; forty-six Democrats; two Independents who caucus with the Democrats). So they would need support from at least eight Democrats or Independents to pass a replacement.
It would be difficult to find eight Democrats who will vote to repeal Obamacare, even with a replacement. Several of the more likely candidates for voting for a replacement voted for the original bill and would face problems with their base if they voted for replacement. However, post-replacement there are ten Democrat Senators in states that Trump won. Those ten will have difficulty voting against a reasonable replacement.
Finally, Republican politicians have been promising to repeal PPACA since 2010. Now that they can, a better question is why would they wait? Waiting hits them with their base, and it's not like they are suddenly going to get votes for doing nothing from those who prefer waiting. The simple political calculus is that there are more rabidly anti-PPACA Republicans than there are pro-PPACA Republicans. They need to appeal to pro-PPACA people in a way that does not lose them their anti-PPACA supporters. Immediate repeal satisfies the anti-PPACA, and a replacement could satisfy the pro-PPACA.
This is the fundamental problem with purely partisan legislation. It has no support from the opposing party, so now that the opposing party has taken control, they have zero incentive to retain it. And every incentive to repeal it.
Even worse is how the Barack Obama administration ran the program. They picked high profile fights with groups asking for religious exceptions, thereby ensuring that there was a committed opposition. This despite promises not to use the bill to promote abortion that were made during passage. They fundamentally lacked empathy for the point of view of the religious objectors.
Of course, they would tell you that the problem is that the religious objectors were taking a ridiculous stance. That's an understandable viewpoint, and it's possible to empathize with their frustration in dealing with what seemed absurd to them. However, regardless of how the administration felt, the result was that the pro-life crowd is absolutely and completely opposed to PPACA. While the pro-life movement is only a small portion of the Republican electorate, it is a much larger portion of the funding and volunteer base.