Two days before Election Day, President Donald Trump traveled to Salina, Kansas, hoping to shore up Republican Sen. Roger Marshall in a state that has not elected a Democratic senator since 1932. The visit captured just how dramatically the Senate battlefield has expanded.

“I hope he doesn’t need it, but I had to make sure that he gets in,” Trump told the crowd. Marshall, a first term Republican, entered the campaign facing unease about his performance from some members of his own party.

The Kansas scramble offered Democrats an extraordinary sign of opportunity, but their own turmoil was unfolding simultaneously in Michigan. Rep. Haley Stevens endorsed Republican Mike Rogers after progressive Abdul El-Sayed defeated her in the Democratic Senate primary, placing a seat Democrats must hold in greater danger.

The two developments neatly illustrated the volatile map. Republicans are pouring time and money into states that should have been safely red, while Democrats are creating trouble in states they cannot afford to surrender.

Democrats need a net gain of four seats to control the Senate because Republicans currently hold a 53 to 47 majority. Even a 50 to 50 chamber would remain under Republican control through Vice President JD Vance’s tiebreaking votes.

That path once appeared nearly impossible, with Republicans defending seats across traditionally red territory. Yet Democrats are favored in North Carolina, competitive in Ohio, Alaska, Iowa and Texas, and forcing Republicans to spend tens of millions of dollars in South Carolina and Kansas.

Polling averages compiled by FiftyPlusOne show Democrats leading in five of their eight possible pickup races, although some of those advantages are narrow. Republicans retain a financial edge, with their groups and allies spending more than $1 billion on advertising since Labor Day, compared with less than $900 million for Democrats, according to AdImpact.

Democratic leaders built their campaign around economic pressure. After Trump’s January 2025 inauguration, Senate Minority Leader Chuck Schumer and House Minority Leader Hakeem Jeffries increasingly portrayed Democrats as fighting for the middle class while Republicans stood with the wealthy.

The party also focused on expiring health care subsidies during the October 2025 government shutdown and repeatedly attacked what Democrats described as Trump’s corruption. Sen. Jon Ossoff of Georgia combined that argument with the party’s message about costs.

Recruitment helped expand the map. Schumer and the Democratic Senatorial Campaign Committee pressed prominent candidates to enter difficult races, including Roy Cooper in North Carolina, former Sen. Sherrod Brown in Ohio and former Rep. Mary Peltola in Alaska.

Cooper is considered likely to capture the seat held by outgoing Republican Sen. Thom Tillis, though North Carolina contests are often close. Brown is challenging Sen. Jon Husted, who was appointed to the seat Vance left when he became vice president, while Peltola is running closely with Republican Sen. Dan Sullivan.

The strategy has also produced painful failures. In Michigan, Schumer and Sen. Kirsten Gillibrand supported Stevens, but El-Sayed won the primary and Stevens subsequently backed Rogers, the Republican nominee.

Maine brought another establishment setback. The Democratic Senatorial Campaign Committee supported Gov. Janet Mills, but progressive oyster farmer and Marine veteran Graham Platner drove her from the race before the primary, then dropped out after denying an accusation of sexual assault.

Former Maine Senate President Troy Jackson replaced Platner as the Democratic nominee with roughly 100 days remaining before Election Day. Elsewhere, Democrats failed to develop competitive opportunities in Montana and Louisiana.

Republicans have created their own problems through nominees who have worried party officials. A former White House official said, “A lot of this was self-inflicted because the president picked some bad candidates.”

In Texas, Attorney General Ken Paxton defeated Sen. John Cornyn after receiving late support from Trump. Republican spending in the race has exceeded $280 million since Paxton won the primary runoff, making it the country’s most expensive contest this cycle, according to AdImpact.

Georgia Republicans also struggled to find a strong challenger to Ossoff. Trump endorsed Rep. Mike Collins before the primary runoff, but Collins entered Election Day as a long shot after his previous positions and baggage raised concerns among Republicans.

Trump closed the campaign’s final Sunday with rallies in Iowa and Kansas, two states that once looked safely Republican. Iowa voted for him by 13 points, while Kansas has not elected a Democratic senator in decades, making both stops striking evidence of Republican vulnerability.

Democrat Adam Hamilton, pastor of a Kansas megachurch, attributed his close race against Marshall to “a war in Iran that nobody wanted and nobody understands why we need” and what he called “the corruption in Washington, the chaos in Washington.” Trump and Vance both turned their attention toward keeping Marshall’s seat Republican.

The Senate majority is now within Democratic reach, but the party’s path remains fragile. Democrats must convert surprising opportunities in Republican territory while protecting Georgia, Michigan, New Hampshire and Minnesota from losses that would wreck their already unforgiving arithmetic.