All three leading Democrats, as well as Kirk's Republican challenger, accused him of inconsistency, a criticism that has nagged Kirk ever since he backed away from his vote in favor of climate change legislation in June.
Kirk said he voted for the Democratic climate change bill because the constituents of his North Shore Congressional District wanted him to. As a senator representing an entire state, he said, he would vote against the same bill.
Kirk's rightward evolution was seen as an attempt to appeal to a Republican base that remained skeptical of his conservative bonafides. And while his courting of Palin could be seen as another effort to shore up support of the base, opponents seized on Kirk's snubbing of Palin during the 2008 presidential race as further evidence of his lack of conviction.
"Mark Kirk begging for Sarah Palin's endorsement makes it clear that he'll seek any endorsement, take up any policy position, and attempt any political maneuver that he thinks will get him more votes," state treasurer Alexi Giannoulias, a leading Democratic candidate, said in a statement. "At the very best, this is shameless political pandering. At worst, it's further proof that Mark Kirk lacks the political courage to make the tough decisions to move our nation forward."
"What does Mark Kirk really believe?" asked Democratic candidate David Hoffman. "Last year he correctly called the addition of Sarah Palin to the McCain ticket a mistake. This year, when faced with a conservative primary challenge he is pandering to her. Kirk has again revealed his true colors: No principles, no standards, whatever it takes to win."
For Democrat Cheryle Robinson Jackson, Kirk's reaching out to Palin seemed to nix any claim he has to being a moderate.
"By openly soliciting Sarah Palin's blessing, Mark Kirk is showing Illinois his true colors," Jackson said in a statement. "Although he claims to be a moderate, Kirk is pandering to the extreme right wing of his party, and in so doing turning his back on the hard-working Illinois families who hope to change the way our government works and don't want to go back to the failed policies of the Bush Administration."
Republican candidate Patrick Hughes responded to Kirk's move to the right by trying to protect turf he wants to establish as his own-- by also accusing Kirk of pandering.
"I believe Mark Kirk, who has consistently supported President Obama's legislative agenda, including cap and trade legislation, is quickly realizing that Republican Primary voters do not share his extreme views," Hughes said in a statement. "In a desperate attempt to prove otherwise, he is seeking the endorsement of Sarah Palin, a true Reagan conservative, to help disguise his liberal voting record."
The Hughes campaign followed up on Thursday with poll numbers that it claims show that self-described conservatives overwhelmingly prefer Hughes to Kirk. According to their numbers, Kirk's favorable to unfavorable rating among conservatives is 2.7:1, compared with 9:1 for Hughes.
The Kirk campaign could not be reached for comment.
On Thursday, the Giannoulias campaign used Kirk's Palin memo to try drum up campaign contributions.
"We can't let Mark Kirk and Sarah Palin take us back to the failed, Republican policies that got us into this economic mess," an e-mail solicitation reads.
Palin has yet to say whether she will tout Kirk when she comes to Chicago to appear on "The Oprah Winfrey Show" Nov. 16.
UPDATE: The Giannoulias campaign wasted little time turning Kirk's Palin play into a negative campaign ad, which it titled "Mark Kirk Going Rogue...on Himself."