The Democratic Senatorial Campaign Committee sent out a fundraising email on Friday telling supporters that six Democrats are now trailing in the polls for the upcoming midterm elections. If Republicans win all six races, “the Senate is theirs,” the email states.

The DSCC, of course, blames the GOP’s lead on the Koch brothers.

“Six Democrats are now trailing in the polls after $28 million in Koch attacks — and if the Republicans win all six, the Senate is theirs,” the email reads. “But we will turn this around and stop them: our Grassroots Victory Project will invest $60 million into 4,000 field staff in 10 states to reverse the GOP’s gains.”

The email then goes on to ask for donations.

Because the email doesn’t provide a source for the referenced polls, it’s not clear which races the DSCC is referring to. However, a number of Democrats are in trouble of losing to the GOP in upcoming Senate races.

A recent automated survey conducted by the right-leaning Harper Polling show Republicans holding leads in five of seven key U.S. Senate races, with other key races being tied.

Business Insider’s Brett LoGiurato provides a breakdown of the numbers, which are just estimates at this point:

• Alaska: Democratic incumbent Sen. Mark Begich trails both possible GOP candidates, Lt. Gov. Mead Treadwell and former Commissioner for the Department of Natural Resources Dan Sullivan, by six points each(47-41). Begich is also upside-down in his job-approval rating, at 41-47.

• Arkansas: Republican U.S. Rep. Tom Cotton leads incumbent Democrat Sen. Mark Pryor 42-36. Pryor’s job approval sits at an upside-down 37-40.

• Louisiana: Incumbent Democratic Sen. Mary Landrieu is in a virtual tie (down 45-44) to U.S. Rep. Bill Cassidy. Moreover, only 40% approve of how she’s handling her job, while 51% disapprove.

• Michigan: Republican and former Michigan Secretary of State Terri Lynn Land leads Democratic U.S. Rep. Gary Peters 42-37 in the race to fill Sen. Carl Levin’s (D) seat. President Barack Obama’s approval rating in Michigan is only 38%, but he carried the state 54-45 in 2012.

• Montana: Republican U.S. Rep. Steve Daines leads Democrat Lt. Gov. John Walsh (who was just appointed to fill Sen. Max Baucus’ seat on Friday) by 14 points (43-29). Another possible Democratic candidate, former Lt. Gov. John Bohlinger, trails 43-32. Walsh and Bohlinger are tied in a Democratic primary matchup.

• North Carolina: Democratic incumbent Kay Hagan is locked in a tie with likely GOP candidate and North Carolina Rep. Thom Tillis. Only 36% approve of her job performance, while 49% disapprove. Obama’s approval rating is also underwater (43-51), as is support for the Affordable Care Act (39-52).

• New Hampshire: Democratic incumbent Sen. Jean Shaheen leads former Sen. Scott Brown 40-35 in a hypothetical matchup. She’s viewed favorably among New Hampshire voters, but Obama’s horrible approval-to-disapproval split (35-57) and Obamacare’s split (32-60) bring her down.

(H/T: Jim Hoft)