(CNN) Maine Sen. Susan Collins' announcement Monday night that she would not vote for her party's last-ditch attempt to repeal and replace Obamacare doomed Republican hopes of abolishing a law they spent eight years campaigning against. Senate Republican leaders acknowledged that defeat Tuesday afternoon, deciding not to even bring the bill up for a vote on the floor.

What's remarkable about the failure of the legislation put forward by Sens. Lindsey Graham of South Carolina and Bill Cassidy of Louisiana, is not that it happened. It's how similar this failure was to the failure of Republicans' first attempt to repeal and replace the Affordable Care Act back in July. And how that intractability of the "no" votes proves one basic fact: There is no repeal and replace bill that can get 50 GOP votes in this Senate. Period.

In the wake of the July defeat, there was little expectation that a re-animation of the repeal and replace effort was even possible. The reason was simple: The GOP Senate conference was caught betwixt and between -- stretched to breaking by hardliners on the right who demanded full repeal and nothing but full repeal and centrists concerned about the elimination of popular provisions like Medicaid expansion and the guaranteed coverage for people with pre-existing conditions.

Those differences -- coupled with the fact that Republicans only controlled 52 seats -- made the policy, and the math, look impossible.

Then, suddenly, out of nowhere came Graham-Cassidy -- a last chance for Republicans desperate to make good on their oft-repeated campaign trail promise to their base. The legislation -- with its block granting of health care dollars to the states -- was touted as the conservative solution to the morass created by Obamacare's federal government control. Finally, a Republican solution Republicans could vote for!

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