After narrowly escaping a competitive four-way GOP primary, Thompson entered the general election campaign as the favorite thanks to a history of appealing to independents and moderate Democrats in his four gubernatorial election victories. His frontrunner status was confirmed in the weeks following the primary when a series of independent polls showed him leading Baldwin.
But Thompson fails to attract many crossover votes in the new NBC News/Wall Street Journal/Marist poll. The former governor earns 9 percent support among respondents who support President Obama in the presidential race, while Baldwin picks up 6 percent of Mitt Romney supporters. Among self-identified independents, Baldwin leads Thompson, 45 percent to 36 percent.
Baldwin and her allies have hammered Thompson on television since the primary, taking him to task for working at a lobbying firm and refusing to release his tax returns. Low on funds after spending heavily in the lead up to the primary, Thompson's television presence hasn't been as robust over the last month.
The poll shows similar results in the presidential contest: Obama leads Romney, 50 percent to 45 percent, while 4 percent remain undecided.
The NBC News/Wall Street Journal/Marist poll was conducted Sept. 16 through 19. It surveyed 968 likely Wisconsin voters, for a margin of error of plus-or-minus 3.2 percentage points.