GOP Sens. Mark S. Kirk of Illinois and Ron Johnson of Wisconsin both trail their likely Democratic opponents a little more than a year out from Election Day, according to polling conducted for End Citizens United PAC .
Kirk trails Democratic Rep. Tammy Duckworth, 41-45 percent, while Johnson trails his likely Democratic opponent, former Sen. Russ Feingold, 39-47 percent, according to the poll.
Both Kirk and Johnson are some of the most vulnerable Senators up for re-election in 2016. Kirk's race is rated a Tilts Democratic contest by the Rothenberg & Gonzales Political Report /Roll Call — the only race projected to switch party hands with more than a year to go before Election Day. Johnson's race is rated a Tossup .
The group — which seeks to elect legislators who will fight for a repeal of the Citizens United court decision — also found in their polling that candidates who want to repeal the 2010 court decision would fare better with voters in 2016.
Campaign finance is likely to be a theme in the Wisconsin race, as Feingold is known for his work on the major campaign finance overhaul that bears his and Arizona Republican Sen. John McCain's name. Polling found that in the Badger State, 68 percent of voters oppose the Citizens United ruling, including 45 percent of self-identified Republican voters and 78 percent of independents.
In Illinois, the survey found 67 percent of voters are opposed to Citizens United, including 56 percent of self-identified Republicans and 69 percent of independent voters.
The End Citizens United PAC says it intends to spend millions on the 2016 elections to try and build support for a constitutional amendment to repeal the decision.
The Illinois poll surveyed 948 voters between Sept. 10 and Sept. 14 with a mix of automated and live phone calls, and has a margin of error of 3.2 percent. The Wisconsin poll was conducted between Sept. 1 and Sept. 3, and surveyed 775 voters with a mix of automated and live phone calls. It has a margin of error of 3.6 percent. The polls were conducted by Clarity Campaign Labs.
Related: Roll Call Race Ratings Map: Ratings for Every House and Senate Race in 2016 Get breaking news alerts and more from Roll Call in your inbox or on your iPhone.