Sens. Pat Toomey (R-Pa.) and Mark Kirk (R-Ill.) are both at risk of losing their Senate seats in November. And they both have become less popular among voters in their respective states over recent months, according to a 50-state Morning Consult poll on Senate approval rankings released Tuesday.

Toomey’s net approval rating has dropped 11 points since April, when Morning Consult last surveyed on Senate approval. Forty-three percent of Pennsylvania voters approve of the job Toomey is doing, while 36 disapprove. Toomey is currently trailing Democratic challenger Katie McGinty by just 1 point, according to the HuffPost Pollster aggregate of polls.

Kirk, who faces a tough election against Rep. Tammy Duckworth (D-Ill.), has seen a 9-point drop in net approval since April ― 35 percent of Illinois voters approve of the job he’s doing, and 38 disapprove. Some Republicans criticized Kirk earlier this year when he broke from his party and called on the Senate to hold a vote on Merrick Garland, President Barack Obama’s Supreme Court nominee.

Sens. Ron Johnson (R-Wis.) and Kelly Ayotte (R-N.H.) are also in vulnerable positions, but have each managed to maintain a relatively high net approval rating since April. The poll finds Johnson with a 45-33 approval/disapproval rating, while Ayotte has a 58-32 margin.

Still, both candidates are struggling to hang onto their seats. Johnson is currently losing to Democratic Sen. Russ Feingold by 7 points. Feingold previously held the Senate seat for 3 terms until he lost to Johnson in 2010. And Ayotte, who has received harsh criticism from her GOP presidential nominee Donald Trump for not offering him an endorsement, is currently in a dead heat against Gov. Maggie Hassan.

Sens. John McCain (R-Ariz.) and Marco Rubio (R-Fla.), who are also up for re-election, rank among the senators with the lowest approval ratings in the country. But they both hold comfortable leads over their rivals: Rubio is up by 6 points and McCain is up by 9 points.

There’s a lot at stake for all of these candidates. Democrats need to capture just four seats to gain control of the Senate if Hillary Clinton wins the presidency, and five if Trump does. There are five Senate seats now held by Republicans that will likely flip to the Democrats, according to the HuffPost Senate prediction model, and three of those races are currently very close. One Senate seat is also likely to flip from Democrats to Republicans.

Morning Consult surveyed 71,900 registered voters online May to September 2016. You can see the full poll report of Senate rankings here.