To win the Senate, Democrats need to keep all 10 seats they're defending in states that President Trump won in 2016 — plus pick up two more seats.

Why it matters: That's not happening. A new Axios/SurveyMonkey poll of key states shows Dems would lose three of those red-state seats while picking up two GOP seats — still short of the majority.

Why it matters: It's looking nearly impossible for Democrats to take back the Senate. So the stakes are even higher for them to win the House if they're going to have any kind of congressional check on President Trump.

The state of play: The polls shows three Democratic senators are poised to lose their seats to Republicans — Heidi Heitkamp in North Dakota, Bill Nelson in Florida and Joe Donnelly in Indiana.

• Be smart... Democrats would pick up seats in Arizona and Nevada, while Republicans keep their seat in Tennessee.

Democratic bright spots: Sens. Joe Manchin in West Virginia and Jon Tester in Montana were losing by double digits to a generic GOP candidate last time we polled these states in February. They're now leading by double digits.

Our data includes an expected range under six different scenarios that measure potential turnout, giving a more complete picture of each race.

• Even under the most optimistic scenarios for Democrats across all 13 states, they would still lose the same seats by a range of one percentage point to 14 percentage points.
• Under Republicans' most bullish forecast, they would actually pick up six seats, the four mentioned above plus Ohio and Missouri.

The bottom line: Democrats face long odds to take back the Senate.

Go deeper: How the Senate races look with multiple voter assumptions.