With a month before election day, we're not only seeing many polls break for Trump, but Senate polling is also looking good for the GOP. For example, there are increasingly positive signs that the GOP could oust longtime Democrat incumbents in Pennsylvania and Montana. Another Senate race is tightening, threatening yet another Democrat incumbent.

Sen. Bob Casey Jr. (D-Pa.) faces one of the toughest re-election battles among Senate Democrats this cycle. While earlier polls had him up by as much as nine points, recent surveys show his Republican challenger, Dave McCormick, gaining momentum. Polls from Emerson College and Atlas Intel show Casey with a slim two-point lead, and Trafalgar has him up by just one point — well within the margin of error.

Meanwhile, in Montana, Sen. Jon Tester (D) is defending another vulnerable Democratic seat. Earlier this year, Tester had a comfortable lead, but his Republican challenger, Tim Sheehy, has taken the lead in every poll since June with an average advantage of 5.2 points. This race, once uncertain, now looks like a strong pick-up opportunity for Republicans, bringing them closer to reclaiming the Senate.

In Ohio, Sen. Sherrod Brown is likely favored, as he has lead in every poll tracked by RealClearPolitics, but Trump has a double-digit lead in the polls in Ohio, and it's conceivable that he could help Republican challenger Bernie Moreno over the finish line.

According to a report from Axios, Sen. Tammy Baldwin (D-Wis.) has seen her lead shrink in both public and internal polls, while Republicans are aggressively pouring money into the state to pull off an upset. With the stakes this high, the race is now on everyone’s radar.

"Baldwin leads by just two points in internal Democratic polling, a source familiar with the campaign told Axios. That is much closer than what public polling has shown for months," the outlet reports. "Democrats are on pace to be outspent by Republicans in the state every week until Election Day, with an infusion of around $20 million from GOP sources."

Republicans are already favored to win back the majority in the Senate, but a loss for Baldwin to Republican Eric Hovde would help insulate a Republican majority for several election cycles. According to Axios, with Montana already looking shaky and Ohio and Michigan toss-ups, Wisconsin was supposed to be one of the safer bets, like Nevada or Arizona — a race that would be close but still manageable for Democrats.

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Several Democratic insiders have told Axios that the situation is more precarious than public polling suggests. A national Democratic strategist pointed to a Marquette University poll showing Baldwin with a six-point lead but insisted that the race is much tighter than that, fueling concerns that the seat — and the Senate majority — could be in jeopardy.

Between the lines: Over the next month, Republicans in the state have a nearly $3.5 million spending advantage on the airwaves, according to a source familiar with ad buys in Wisconsin.

• A super PAC linked with Senate Minority Leader Mitch McConnell (R-Ky.) is making a new $17 million investment in the state, along with Hovde making his own infusion of over $2 million.
• But Democrats have already spent over $100 million in the state this year, giving them an overall spending advantage since January of almost $30 million, according to AdImpact.

Conventional wisdom held that Democrats voted Joe Biden out of the race to salvage down-ballot races, but it looks like the momentum in the final weeks is benefiting both Trump and GOP Senate candidates.