We can t wait for next year s midterm elections! This will be a huge chance for Republicans to build a bigger majority in the Senate.The Senate map heavily favors Republicans who look solid except for a couple seats. Democrats don t have it so good. They ll have to defend 25 seats!Here are the seven most vulnerable Senate seats according to The Hill:Sen. Dean Heller (R-Nev.) Heller is the only Republican up for reelection in 2018 who represents a state that Hillary Clinton won last November. Making matters worse for Heller, he s had a rough 2017.Sen. Claire McCaskill (D-Mo.) McCaskill is one of the few statewide Democratic officeholders left in Missouri, which Trump won by 19 points in November.Sen. Joe Donnelly (D-Ind.) Donnelly leveraged a bipartisan approach to politics and his blue-collar appeal into a Senate seat in 2012, but he ll have to fight yet another tough battle if he wants to keep his Senate seat in a state Trump won by 19 points.Sen. Jeff Flake (R-Ariz.) Flake wouldn t rank this high in a normal election year, but a Republican president threatening to support a primary challenge to an incumbent GOP senator isn t normal, either.Sen. Joe Manchin (D-W.Va.) In 2016, West Virginia went for Trump by a larger margin than any other state   42 points.Sen. Heidi Heitkamp (D-N.D.) Heitkamp hails from another deep-red state   North Dakota went for Trump by about 36 points.Sen. Jon Tester (D-Mont.) Republicans have a lot to like about their Montana prospects. Trump won the state by more than 20 points in November, and Republican Greg Gianforte just won the state s at-large congressional seat in a special election   even after he assaulted a reporter.