Within minutes of the Supreme Court's ruling to uphold the president's health care law on Thursday, both Congressional Republicans and the GOP's presumptive presidential nominee, Mitt Romney, vowed to repeal the law as well.

Senate Minority Leader Mitch McConnell restated that vow Friday, saying on the Laura Ingraham radio show that if Romney wins and the GOP gains a majority in the Senate, repealing Obamacare "is the first item on the agenda."

But can they?

If Romney wins the White House, his power to gut or eliminate the law is severely limited without the help of Congress. And with slim odds that the GOP will win a filibuster-proof majority in the Senate, congressional Republicans face a steep climb to repeal the president's signature law.

Such long odds have not deterred the law's opponents, though. After the Supreme Court ruled on the health care law, House Republicans quickly promised that they will once again act to repeal the law in its entirety July 11.

That vote is expected to pass easily, much like when the House first voted for repeal Jan. 19, 2011, approving the measure 245-189. House Republicans have already voted 30 times to disrupt, dismantle, defund and repeal provisions in the health care law. No similar attempts have passed in the Senate.