Wisconsin Republicans worry that a crowded Senate primary could make it harder for them to beat Democratic Sen. Tammy Baldwin.

Republicans feel that Baldwin is vulnerable — President Donald Trump became the first Republican to win Wisconsin since Ronald Reagan in 1984. And Republican Sen. Ron Johnson also won re-election against former Sen. Russ Feingold last year in a rematch of their 2010 Senate race.

But Republicans worry that they might make the same mistake they made in 2012 when too many candidates weakened eventual nominee former Gov. Tommy Thompson against Baldwin, The Associated Press reported.

“You talk to the grassroots and they’re still riding high from the last election,” Brian Westrate, chairman of the Wisconsin’s 3rd Congressional District Republican Party told the AP. “Those of us who have seen the sausage get made a lot of times are pragmatically concerned about the Senate race.”

Westrate said he would feel better if there was a generally agreed-upon candidate but instead, there at least four Republicans are making moves to get into the race, including millionaires Eric Hovde and Nicole Schneider, and Kevin Nicholson, backed by mega donor Richard Uihlein, and at least four others being recruited or thinking about it.

“Any one of them could be a fine candidate,” Westrate told the AP. “It’s just unfortunate as it stands now there isn’t any one of them. There’s six of them.”

Meanwhile, the incumbent has already raised $2.2 million in the first quarter of 2017 and has $2.4 million in cash on hand.