Not long ago, President Biden and congressional Democrats were riding high. They benefited from falling gas prices, a rash of legislation, a foolish but popular student debt bailout, several weak GOP candidates, and voter backlash to the reversal of Roe v. Wade. Now it’s autumn, and there is a chill in the air and a change in the political temperature. Republicans, the polls suggest, have a path to a Senate majority. They are on track to take the House. The GOP has recovered from its summer swoon.

The revival began two weeks ago. Encouraging words came from an unlikely source. On September 12, Nate Cohn of the New York Times wrote that polls may be underestimating the GOP yet again in states like Wisconsin, Ohio, North Carolina, and Florida. When a potential polling error is considered, Cohn went on, Republicans appear much more likely to take over Capitol Hill.

Cohn is neither a partisan nor an ideologue. He plays it straight. But his analysis launched the sort of conversation about polling error that Republicans love. Cohn reinforced the right’s longstanding suspicion that GOP voters do not talk to pollsters. So long as the final polls are within the margin of error, this thinking goes, Republicans have a chance of a victory.

Then, on September 15, Governor Ron DeSantis of Florida upended the electoral cycle. His one simple trick: sending a plane of Venezuelan asylum-seekers to Martha’s Vineyard. Suddenly, Democratic-friendly topics vanished from the headlines. Abortion, student loans, and Mar-a-Lago disappeared from cable news chyrons. They were replaced by controversy over an issue — border security — that favors the GOP.

The stunt was a public relations coup. It reset the national debate. It sent the left into a frenzy. And it boosted DeSantis’s star power at just the right moment.

The timing was important. DeSantis’s move coincided with an increase in GOP Senate advertising. Between September 5 and September 26, according to AdImpact data reported by NBC News, Republicans outspent Democrats on the air in eight of nine competitive Senate races. Arizona was the exception.

Mitch McConnell’s Senate Leadership Fund (SLF) led the charge. It was responsible for most of the spending in North Carolina, Ohio, Pennsylvania, Georgia, and Nevada. SLF was less of a factor in Wisconsin, but that’s because incumbent Senator Ron Johnson had the resources to launch a fusillade of negative ads at his opponent, Lieutenant Governor Mandela Barnes.

The GOP barrage hits Democrats as soft on crime. And it’s working. Johnson has pulled ahead of Barnes in Wisconsin. Mehmet Oz has narrowed the gap between him and John Fetterman in Pennsylvania. Herschel Walker has done the same in Georgia. Meanwhile, both Ted Budd in North Carolina and J.D. Vance in Ohio hold slim leads over their Democratic opponents.

Since Arizona and New Hampshire look out of reach, the GOP has to hold Wisconsin, Pennsylvania, North Carolina, and Ohio, and pick up either Georgia or Nevada. That outcome — all else being equal — would give Republicans 51 seats and restore McConnell as majority leader. Winning both Georgia and Nevada would bring the GOP to 52 seats, of course. Any additional pickups, such as talented newcomer Joe O'Dea upsetting Michael Bennett in Colorado, would be icing on the cake.

A 52-seat majority would put Senate Republicans back where they started after the 2016 election. It would be the same number of seats that they won in the 1994 “Republican Revolution.” A two-seat margin of control might not be the gift that Republicans hoped for at the beginning of the year. But they will happily accept it.

This 52-seat scenario is full of caveats. It depends, most importantly, on whether Johnson, Budd, Vance, and Oz can fend off their opponents. The weakest link in this fence may be Oz. He’s a first-time campaigner in a swing state who has yet to consolidate Republican voters, much less independents. If Oz succumbs, the map becomes more difficult for Republicans. And something that has never happened before — back-to-back 50-50 Senates — would be a possibility.

Oz should not be dismissed. The polls show him moving in the right direction. His opponent’s personal health and stances on drugs and criminal justice are big vulnerabilities. Also, Republican voters are likely to come home by Election Day. And independents, as Henry Olsen has pointed out, tend to break late against the president’s party.

Biden’s job approval remains in the low 40s. Republicans have cut down the Democratic advantage in the congressional generic ballot to 1 point. Republicans are winning on the economy, inflation, and crime. And all these subjects are at the top of voters’ minds. “The Republicans’ 14-point advantage in trust to handle crime matches its largest since 1991,” according to the Langer Research poll released this week by the Washington Post and ABC News. “Among independents it’s a whopping 34-point GOP lead.”

The problem facing Democrats is that they are tied to an unpopular president in an environment that favors the GOP. Progressive policies — massive spending, crippling oil and gas production, decarceration, cuts to local police, normalizing and subsidizing homelessness and addiction, encouraging illegal border crossings — have created an economic and social crisis that is impossible to ignore. That is why McConnell says Republicans have an even shot of taking the Senate. It is why Kevin McCarthy is almost certain to become the next speaker of the House.

Four successive presidents have lost control of Congress. In each of the past four elections, at least one branch of government or one chamber of Congress has switched hands. You think Joe Biden is going to buck this trend? I wouldn’t bet on it.

Matthew Continetti is a senior fellow at the American Enterprise Institute and the founding editor of The Washington Free Beacon. For more from the Free Beacon, sign up free of charge for the Morning Beacon email.