Senate races begin to shift towards the GOP in campaigns' final stretch

As the presidential race increasingly appears to be shifting towards Trump, some down-ballot races seem to be following suit, bolstering the already strong prospects of a Republican-held Senate in the next Congress.

Polling data has increasingly shown Trump gaining ground in virtually every key battleground, including Pennsylvania, Michigan, Wisconsin, Nevada, and Arizona, where key battles to decide the fate of the Senate are being waged.

Republicans are heavily favored to win the Senate, in no small part due to the layout of the electoral map this cycle. Several Democratic incumbents in swing states face reelection, notably Sens. Bob Casey, D-Pa.; Jon Tester, D-Mont.; Tammy Baldwin, D-Wis.; and Sherrod Brown, D-Ohio.

Polymarket betting odds currently give the Republicans  77% chance of taking the Senate and a 39% chance of sweeping both chambers and the presidency. Here’s a look at the races pivotal to that result and shifts in each that have the bookies bullish.

Montana

Tester narrowly fended off a challenge from then-Rep. Matt Rosendale, R-Mont., in the 2018 midterm cycle, managing to hold his seat in a state that broke for Trump by double digits. Though Rosendale briefly entered the Republican primary this cycle, he dropped out after less than a week as Republicans lined up behind Tim Sheehy for the party nod.

Tester currently trails Sheehy by an average 7.0%, according to RealClearPolitics. Earlier this year, Tester held narrow leads against Sheehy and was even up 9.0% in one February survey. But the Republican consolidation behind Sheehy may prove insurmountable, especially as Trump is currently leading Harris in the state by an average 17.4% and may have coattails of benefit to Sheehy.

Ohio

The Trump-backed Bernie Moreno managed to triumph in a crowded Republican primary and will face Brown in the November contest. Like Tester, Brown has managed to hold onto his seat in a state that has increasingly shifted towards the GOP in recent cycles.

At present, Brown holds an average 2.6% lead over Moreno, though that figure is significantly less than the surveys from just months ago placing him 4-6 points ahead. The RCP average, moreover, includes more recent data showing the race within 1-2%.

Trump, for his part, currently leads Harris in Ohio by 7.4% and the state is not considered a battleground this cycle.

Michigan

Bombshell polling data has emerged in recent days showing Trump poised to take the Wolverine State in the White House race and the RCP aggregate this week put the state into the Republican column.

At the Senate level, Republicans may benefit from the retirement of incumbent Sen. Debbie Stabenow, D-Mich. Rep. Elissa Slotkin, D-Mich., is vying with former Rep. Mike Rogers, R-Mich., for her seat and the race is one of the most competitive this cycle. Slotkin currently enjoys a narrow 1.9% lead, though several component surveys of that average show the race either tied or within a single point.

In late September, however, Slotkin led Rogers by as much as 5.1%, meaning the Republican has managed to more than halve his opponent’s lead in a matter of weeks.

Wisconsin

Trump still trails in Wisconsin, according to most surveys, as does his Senate counterpart, businessman Eric Hovde. But both races have moved in a manner beneficial to them in recent weeks. The Dairy State broke for Trump in 2016, before flipping back to the Democrats in 2020. Sen. Ron Johnson, R-Wis., managed to stave off a challenger in 2022 as well.

But Hovde is the one challenging an incumbent rather than the other way around. The mustachioed mogul currently trails incumbent Sen. Tammy Baldwin, D-Wis., by an average 3.4%. As recently as August, however, he trailed by an average 6.7%. Like Rogers in Michigan, he appears to have more than halved his Democratic opponent’s advantage in a matter of weeks.

Pennsylvania

Republican prospects in the Keystone State are somewhat murkier. While Trump has consistently posted modest leads there, the Senate race has fluctuated more than many of the battleground races.

As recently as late August, Casey led Republican challenger David McCormick by an average 7.6%, though that lead dropped to as low as 3.0% in mid-September, before again widening to its current 3.9%. Trump leads Harris by 0.4%.

Arizona

Republican prospects appear dimmer in Arizona, albeit not without some reasons for optimism. Rep. Ruben Gallego, D-Ariz.; currently maintains a commanding 6.8% average lead over Republican Kari Lake.

Like in Pennsylvania, the race has fluctuated. In early September, Gallego led by 7.3%, though the race closed to 4.3% later in the month. Trump, for his part, holds a 0.5% lead over Harris at the national level, meaning the Lake trails 7.2% behind the top of the ticket.

Lake and Gallego squared off this week in a debate that legacy media and some local outlets loosely pronounced as a Gallego victory. Some clips, however, circulated on social media of Lake managing to score a few hits on her Democratic opponent that supporters say offered hope for a possible turnaround.