Talk about summer blues.

The number of Republican-held Senate seats that are toss-ups or lean Democratic has surged from three in May to six as the post-Labor Day midterm homestretch is about to begin, according to a top political analysis.

In May, only the GOP-held seats in North Carolina, Maine, and Ohio were considered toss-ups or leaning towards Democrats. Now, Texas, Iowa, and Alaska have also turned into toss-ups, per the Cook Political Report.

President Trump won each of those states except Maine in 2024 — four of them by double digits.

“I worry about that, for sure,” Senate Majority Leader John Thune (R-SC) admitted to Keloland News last week, when asked about the odds of Republicans losing their grip on the upper chamber.

“I’m a realist, and … I don’t ever try and sugarcoat things. I think it’s a competitive environment right now.”

As The Post previously reported, Republicans are behind in eight of the nine competitive Senate races this cycle, according to the RealClearPolitics polling aggregate. Iowa is the only one where the Republican candidate is up in the polls.

Notably, almost all of those races, except Georgia and North Carolina, are within the typical margin of error. Data guru Nate Silver has aggregated similar results from the polls based on his methodology of weighing more credible polls more heavily.

“National Republicans have been sounding the alarm that midterms are hard since last year, and we’ve been firm that not a single race should be taken for granted,” a GOP operative involved in Senate races previously told The Post.

“Republicans continue to believe we’ll hold the Senate.”

Despite the bleak polling, some Republicans have taken solace in the fact that many polls have undercounted their voters in recent cycles.

An analysis by Echelon pollster Patrick Ruffini assessed that 3,312 polls had underestimated Republicans by 3.7 points on average over the past four election cycles. The error rate jumped to 5.9 percentage points.

A famous example of this was Sen. Susan Collins’ (R-Maine) 2020 bid when the RCP had her down by roughly 5 percentage points, and she won by 8.6. More recently, polling aggregates overestimated Dr. Abdul El-Sayed’s support in Michigan by about 9 points in his primary against Rep. Haley Stevens (D-Mich.)

CNN data guru Harry Enten recently noted that if polls have a similar error rate to past election cycles, Republicans could conceivably hold onto the House, despite widely being viewed as the underdogs there.

Additionally, President Trump is armed with a huge cash cannon in his MAGA Inc super PAC, and the official GOP campaign arms are flush with more cash than their Democratic counterparts. Trump’s political team has only really just begun tapping into that firepower, and it is just starting to get splurged now.

During some of those past elections where Republicans were underestimated, Trump was on the ballot. There are questions about whether the GOP’s low-propensity voters will turn out enough for them to win.

Democrats are working to seize on Trump’s approval rating being significantly underwater, gas prices remaining high, affordability being the runaway top issue for most voters, and divisions within the GOP over the war in Iran as well as the Epstein files.

A recent Gallup poll found that Democrats have their biggest party identification advantage over Republicans since about 2008, with a roughly 10-point edge.

There are also historical headwinds that typically go against the party in control of the White House during midterm elections; however, that trend has been true for the House, but not necessarily the Senate.

Both Trump and former President Joe Biden gained Senate seats during the midterms of their first terms, despite taking a beating in the House.