Rep. Tammy Baldwin (D-Wis.) leads former Wisconsin Gov. Tommy Thompson (R) in their Senate race in a new poll, the latest to show her with momentum in the state.

The poll shows Baldwin leading Thompson by 48 to 46 percent in a poll conducted for NBC News and The Wall Street Journal by Marist College. Two other nonpartisan public polls released this week showed the race tied and Baldwin up by 9 points, a big shift from one month ago, when Thompson led in all public polling by a comfortable margin.

Baldwin has been able to outspend Thompson on the air since he clinched the GOP nomination because he spent most of his campaign funds to win the August primary, and Thompson himself admitted he'd slipped in the polling earlier this week, partly blaming his financial disadvantage and partly blaming Mitt Romney for his standing. Romney trails President Obama in the same NBC poll by 5 percentage points despite having home-state Rep. Paul Ryan (R-Wis.) on the ticket.

"The presidential thing is bound to have an impact on every election," Thompson told Madison TV station WKOW on Wednesday when asked about recent polling that showed him slipping behind Baldwin. "You know, whether you're a Democrat or Republican, if your standard-bearer for the presidency is not doing well, it's going to reflect on the down ballot."