A Marquette University Law Poll released Thursday found that although Walker would still win his home state primary if it was held today, his support had dropped from 40% to 25%. Voters, meanwhile, said they would go for either Carson (13%), Donald Trump (9%) or Ted Cruz (8%) -- reflecting a broad shakeup in the Republican field nationwide since the first Republican debate.
But in a head-to-head matchup, Democratic front-runner Clinton would beat him 52%-42%.
Walker said he was not fazed by the poll and compared it to low poll numbers for him just before he won a resounding recall battle in 2012.
"I thinks it's a lot of the attacks from the outside," he said after a campaign stop. "As people come back and look at what we have to offer, we're going to have the support of people in our state just like we have the support of people in places like New Hampshire, Iowa and South Carolina."
The poll of 802 Wisconsinites, split with roughly equal shares of Republicans and Democrats, found that only 39% of residents had a favorable opinion of Walker, 60% say he gets things accomplished and 63% of residents were unhappy he was running for president.
Walker has been slipping in both national polls of Republican voters and Iowa polls following his debate performance earlier this month, which received lukewarm reviews. Meanwhile, on the trail, he has stepped up his anti-establishment rhetoric in a move to gain more support among disenfranchised conservatives.
The two-term Wisconsin governor entered the race last month at the front of the pack with former Florida Gov. Jeb Bush, in part based on his ability to straddle the line between the party's fiscal and social conservatives.
But Trump's dominance has created a new split, to which Walker has been trying to adapt: party outsider versus establishment candidate. Walker has been quickly trying to move into the former category, in large part by just slightly shifting his message to include a few lines about taking on Republicans in Washington and Wisconsin.
He said Wednesday that the shift is in response to his debate performance and the threat of Trump.
"I think before I was trying to be respectful of other candidates. We haven't gone after the other candidates. But I think people want to see a sense of urgency, feel a sense of urgency. They want to see it, they want to feel it, and so we've started to articulate that," Walker said.