Control of the U.S. Senate has slipped into a dead-even toss-up with roughly four weeks left before the midterms, according to a new forecast from Decision Desk HQ that finds the most likely outcomes are either a 50-50 tie or a narrow Democratic majority.

Under that forecast, Vice President JD Vance would be positioned to break a tie in Republicans' favor if the chamber splits 50-50, giving the GOP a narrow edge in the average modeled outcome even though a 51-49 Democratic majority is also among the top modeled scenarios, according to Mediaite's analysis of the model. The same forecast gives Democrats a 67% chance of retaking the House.

The tightening comes as Republican anxiety grows in public. Sen. Ted Cruz said on a podcast this week that "I'm really worried" about the Senate map, naming North Carolina, Georgia, Maine, Iowa, Ohio, Alaska, Nebraska, Kansas and Texas as states where he sees Democratic opportunities, according to Mediaite. Cruz said he is more worried about Democrats flipping the Senate, which requires netting four seats, than about House control.

A Volatile Final Stretch

Several of the states Cruz flagged have featured prominently in this cycle's most contested contests, including Texas, where Attorney General Ken Paxton's Senate bid has drawn repeated visits from President Trump amid a tightening race. The battle for the Senate majority carries outsized stakes for the final two years of Trump's term, determining whether Republicans retain the ability to confirm judicial and executive nominees without Democratic votes.

A PURE TOSS-UP WITH LESS THAN 60 DAYS TO GO

Both parties' campaign committees have poured record sums into the handful of races seen as likeliest to decide control, and strategists on both sides expect the map to keep shifting as early voting begins in several key states over the coming weeks. Election analysts caution that Senate forecasts this far out have swung significantly in past cycles, and both parties are treating the current map as fluid heading into the final stretch of campaigning. Decision Desk HQ's model is updated regularly as new polling and fundraising data become available, meaning the current toss-up rating could firm up — or flip — before Election Day.