—Douglas Rissing—iStock/Getty ImagesAmid projections of a Democratic blue wave, as voters head to the polls, several pivotal races are too close for all the experts to comfortably predict.A TIME analysis of race ratings by 10 reputable election forecasters found that of the 35 U.S. Senate seats up for election on Nov. 3, eight are not rated unanimously in favor of one party. Those eight races are in Alaska, Iowa, Kansas, Maine, Michigan, Ohio, South Carolina, and Texas. And Democrats would have to win at least four of them, assuming other results go as expected, to take control of the upper chamber of Congress.The analysis examined ratings from Cook Political Report (CPR), Decision Desk HQ (DDHQ), FiftyPlusOne (FPO), Fox News Power Rankings (FNPR), Inside Elections (IE), Race to the WH (RWH), Sabato’s Crystal Ball (SCB), Silver Bulletin’s FLIPR Deluxe model (SB), Split Ticket (ST), and The Economist (TE).Read More: 12 House Races That Forecasters See Going Different WaysIn Alaska, four forecasters—DDHQ, FPO, SCB, and ST—rate the race between Democratic former Rep. Mary Peltola and Republican incumbent Sen. Dan Sullivan as leaning Democratic, while the remaining six call it a toss-up. (TE uses the term “uncertain,” which this analysis treats as the equivalent of a toss-up rating.)In Iowa, different forecasters can see the race between Republican Rep. Ashley Hinson and Democrat Josh Turek going different directions. RWH rates it as Tilt Democratic, while SCB says it leans Republican, and TE rates it Likely Republican. The other seven forecasters call the race a toss-up.In Kansas, where Democrat Adam Hamilton is challenging Republican incumbent Sen. Roger Marshall, four forecasters—FPO, SCB, SB, and ST, say the race leans Democratic. The other six forecasters call it a toss-up.In Maine, seven forecasters favor Democrat Troy Jackson over Republican incumbent Sen. Susan Collins, rating the race either Lean or Likely Democratic. CPR, IE, and FNPR call it a toss-up.Read More: 10 Candidates Who Could Make History in the MidtermsIn Michigan, only FNPR rates the race between Democrat Abdul El-Sayed and Republican Mike Rogers as a toss-up. IE says it tilts Democratic; CPR and SCB say it leans Democratic; and the rest all rate it Likely Democratic.In Ohio, where Democratic former Sen. Sherrod Brown is challenging Republican incumbent Sen. Jon Husted, seven forecasters favor Brown—rating the race either Tilt or Lean Democratic— while CPR, DDHQ, and TE call it a toss-up.In South Carolina, FNPR and RWH say the race between Republican Sen. Darline Graham and Democrat Annie Andrews is a toss-up, while eight forecasters favor Graham keeping the seat she filled after her brother’s passing. IE says it tilts Republican, TE rates the race Likely Republican, and the other six all say it leans Republican.In Texas, seven forecasters favor Democrat James Talarico over Republican Ken Paxton. IE rates the race as Tilt Democratic; DDHQ, FPO, RWH, and SCB say it leans Democratic; and SB and ST rate the race Likely Democratic. CPR, FNPR, and TE call it a toss-up.Read More: The 7 Key Governor Races to Watch in the Midterm ElectionsOf the remaining 27 Senate races, 13 are unanimously rated in favor of Democrats. Nine of those are rated safely or solidly Democratic by all 10 forecasters: John Hickenlooper in Colorado, Chris Coons in Delaware, Juliana Stratton in Illinois, Ed Markey in Massachusetts, Cory Booker in New Jersey, Ben Ray Luján in New Mexico, Jeff Merkley in Oregon, Jack Reed in Rhode Island, and Mark Warner in Virginia. Another four Democrats—Jon Ossoff in Georgia, Peggy Flanagan in Minnesota, Chris Pappas in New Hampshire, and Roy Cooper in North Carolina—are unanimously favored, although not every forecaster rates their races as safe or solid.The other 14 races are unanimously rated in favor of Republicans. Seven are rated safely or solidly Republican by all 10 forecasters: Barry Moore in Alabama, Tom Cotton in Arkansas, Jim Risch in Idaho, Kevin Hern in Oklahoma, Bill Hagerty in Tennessee, Shelley Moore Capito in West Virginia, and Harriet Hageman in Wyoming. In seven more, all 10 forecasters favor the Republican candidate—Ashley Moody in Florida, Andy Barr in Kentucky, Julia Letlow in Louisiana, Cindy Hyde-Smith in Mississippi, Kurt Alme in Montana, Pete Ricketts in Nebraska, and Mike Rounds in South Dakota—though not all rate the contests as safe or solid.TIME’s analysis reflects the forecasters’ ratings as of 7 a.m. ET, Nov. 3. Ratings describe the forecasters’ assessments of each race based on polling and fundamental assumptions, but they are not guaranteed outcomes.