Whether Kirk remains in the race or not, the message from the episode is clear: The GOP base will not quickly support any candidate who supports the massive tax hikes required by the Obama-Pelosi-Waxman bill. There is widespread agreement that concern over climate change cannot justify a crippling of the American economy or confiscatory taxes on all energy use. Rhetoric about the environment, in other words, cannot substitute for a party-defining commitment to limited government and lower taxes. Republicans who bolt on this issue will not be easily forgiven and their decision not quickly forgotten. This isn't a "big tent" issue in other words. The Obama-Pelosi-Waxman bill is not a "free vote" because it is so awful in ints impact and implications.
Whether Congressman Kirk decides to run, and if so, whether he will recover his momentum will not reverse the message of this week: The GOP is indeed and ought to remain a very big tent, but there are exits to even very large tents. Freedom-and-growth destroying expansions of the federal government cannot be part of the Republican agenda, and those who support such deeply misguided and radical plans cannot expect to carry the standard for the party in high profile campaigns.