UPDATE: Originally posted in December 2011. Re-posted here after Governor Romney finally raised this exact point in the final GOP Primary Debate on CNN.

Rick Santorum has been the hardest critic of Mitt Romney in the Republican primary debates over the subject of Romneycare in Massachusetts, saying that it is the same as Obamacare. However, Rick Santorum devoted his time, effort and public credibility to a Senator who was the crucial vote in passing Obamacare while Mitt Romney devoted his time, effort and public credibility to a Senator who got elected to become the final vote AGAINST Obamacare.

In his home state, Mitt Romney endorsed, campaigned for and got elected Scott Brown against Obamacare. Scott Brown was elected to the seat vacated by Teddy Kennedy in liberal Massachusetts and voted against Obamacare (only to have it passed through loopholes anyway).

In his home state, Rick Santorum endorsed, campaigned for and got elected Arlen Spector, who was facing a primary challenger by the more conservative Pat Toomey. Arlen Spector was re-elected and became the only Republican  to vote for Obamacare, switching to the Democrat party to avoid another primary competition with Pat Toomey.

Pat Toomey later won the general election to become a strong conservative-republican anti-obamacare senator just a few months before Scott Brown was elected.

If Santorum had stayed true to his parties base and endorsed Toomey LAST time around, Toomey could have replaced Arlen Specter for the nomination, won that election, making his current term his 2nd instead of his 1st and we would have never had Obamacare.

So when Rick Santorum attacks Mitt Romney for Romneycare and thus Obamacare – remember that he has no credibility on the issue.

The history is verifiable: Mitt Romney passed a healthcare law in his liberal home state, pulled it to the right as much as he could (including vetoing several measures that were unfortunately then overridden the by the 85% Democratic Legislature), consistently opposed imposing any of the mandates in the bill on the nation at large and backed up that support by electing an anti-Obamacare senator from his very left wing home state. Rick Santorum on the other hand betrayed his stated beliefs and helped to elect a Republican so liberal that he changed to the democrat party and became the last needed vote to pass Obamacare.

To the extent any of the current GOP candidates are responsible for Obamacare, it is Rick Santorum.

UPDATE From the Romney Campaign:

UPDATE: David Frum, oddly, places the blame of Obamacare not on the Senator who switched parties to vote for it (Specter) but on current senator Pat Toomey.

Sequence of events:
1) Arlen Specter votes in favor of President Obama’s stimulus package.

2) Pat Toomey announces his challenge to Specter, backed by Club for Growth and other outside groups.

3) Fearing the primary challenge, Specter reaffiliates as a Democrat—just in time to cast the 60th vote in favor of the Affordable Care Act.
No primary challenge, no Obamacare. It’s that simple.

The logical problem is that Toomey is the current senator in Specters old senate seat, proving he can and could have won if he won the primary against Specter in 2004 if only he had the support of people like Rick Santorum…