Five Senate Democrats trail their GOP challengers and would lose their bids for reelection were the 2018 midterms held today, according to polls from SurveyMonkey.

New polls published Thursday morning in Axios show Sens. Claire McCaskill Claire Conner McCaskillMomentum growing among Republicans for Supreme Court vote before Election Day Democratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally MORE (D-Mo.), Jon Tester Jonathan (Jon) TesterPence seeks to boost Daines in critical Montana Senate race This World Suicide Prevention Day, let's recommit to protecting the lives of our veterans Filibuster fight looms if Democrats retake Senate MORE (D-Mont.), Joe Manchin Joseph (Joe) ManchinNames to watch as Trump picks Ginsburg replacement on Supreme Court Momentum growing among Republicans for Supreme Court vote before Election Day Gardner on court vacancy: Country needs to mourn Ginsburg 'before the politics begin' MORE (D-W.Va.), Joe Donnelly Joseph (Joe) Simon DonnellyNames to watch as Trump picks Ginsburg replacement on Supreme Court Momentum growing among Republicans for Supreme Court vote before Election Day Barrett seen as a front-runner for Trump Supreme Court pick MORE (D-Ind.) and Heidi Heitkamp Mary (Heidi) Kathryn HeitkampCentrists, progressives rally around Harris pick for VP 70 former senators propose bipartisan caucus for incumbents Susan Collins set to play pivotal role in impeachment drama MORE (D-N.D.) would all lose reelection to GOP challengers if voters were heading to the polls this week.

With the exception of McCaskill, who is squaring off against Missouri Attorney General Josh Hawley (R), the senators were polled against generic, unnamed GOP challengers.

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President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE's approval rating hovers above 50 percent in those states, all states he won in 2016, while the five Democrats all suffer from approval ratings below the 50 percent line.

At the top of the list is Tester, who trails an unnamed GOP challenger by 13 points in a state where Trump enjoys an approval rating of 58 percent, considerably higher than his 43 percent national average.

The two least-vulnerable Democrats in the poll were Sens. Bob Casey Robert (Bob) Patrick CaseySecond GOP senator to quarantine after exposure to coronavirus GAO report finds brokers offered false info on coverage for pre-existing conditions Catholic group launches .7M campaign against Biden targeting swing-state voters MORE (D-Pa.) and Bill Nelson Clarence (Bill) William NelsonDemocrats sound alarm on possible election chaos Trump, facing trouble in Florida, goes all in NASA names DC headquarters after agency's first Black female engineer Mary W. Jackson MORE (D-Fla.), who both enjoy at least a 10-point gap between them and their announced challengers.

Democrats would need to defend all of these seats as well as pick up two others in order to take back the majority in the upper chamber in 2018.

SurveyMonkey conducted the poll online between Feb. 12 and March 5 and surveyed 17,289 voters in Florida, Pennsylvania, Ohio, Michigan, Wisconsin, Missouri, Indiana, West Virginia, Montana and North Dakota. The poll did not display a margin of error.