The replacement of Vice President Harris for President Biden at the top of the ticket has tilted the races for the White House and Congress in the direction of Democrats, though all three fights will be close, according to Decision Desk HQ (DDHQ)/The Hill’s updated analysis of its election forecast.

Harris has a 55 percent chance of defeating former President Trump and winning the White House, a sharp turn up from Biden’s 44 percent chance of winning when he left the race and endorsed Harris on July 21.

Democrats also have better chances of winning the House and Senate with Harris as their standard-bearer, though they remain the underdogs in both cases.

The GOP remains the big favorite to take back the Senate majority, though the DDHQ/The Hill analysis puts the chance at 67 percent, compared to 78 percent when Biden dropped out.

The House race is seen as much closer, with the GOP having a 56 percent chance of retaining its majority. That’s slightly down from 61 percent when Biden was the Democratic standard-bearer.

Here’s a closer look at the new analysis after a tumultuous and historic eight weeks in politics that included a disastrous debate by Biden, an assassination attempt of Trump, Biden’s decision to drop out and endorse Harris and political conventions for both parties.

White House

Harris currently has a 55 percent chance of winning the White House, which would make her the first female president. That’s a big jump from where the model left off with Biden when he dropped out July 21, when the incumbent had a 44 percent chance.

Still, the race remains competitive.

“Neither campaign can go to sleep easy tonight thinking they’re ahead or they’ve got the advantage,” said Scott Tranter, the director of data science for DDHQ.

Harris has surged in the polls over the past month both nationally and in key swing states, building off of new enthusiasm that Democrats have for their ticket. When she first joined the race, she trailed in The Hill/DDHQ national polling average by 2 points, but now she leads by nearly 4 points.

She has improved in each of the seven states most likely to determine the result of the election, but the shift in three states — Pennsylvania, Michigan and Wisconsin — is the main reason for Harris’s better prospects.

These states represented Biden’s best path to victory, but Trump was favored to win two of them, and Biden was barely the favorite in Michigan. Harris now is similarly favored a bit in Pennsylvania, with a 53 percent chance of taking its 19 electoral votes; she is also more clearly favored in Michigan and Wisconsin, with her chances of winning them at 67 percent and 58 percent, respectively.

Biden trailed in each of these states by a few points, and the gap was growing as calls mounted for him to leave the race.

Harris has also closed the gap in the Sun Belt states that looked increasingly out of reach for Biden. She is trailing Trump by about 3 points in Georgia and 1 point in Nevada, while the two are essentially tied in Arizona.

Overall, she has a 35 percent chance of winning Georgia, a 60 percent chance of winning Nevada and a 49 percent chance of winning Arizona. But all of that is subject to shift.

“We’ve seen these probabilities shift 10 points once. We can certainly see them move 10-15 points again,” Tranter said.

He said the model also is up to date to include the impact of independent candidate Robert F. Kennedy Jr.’s decision to suspend his campaign and endorse Trump. But because Kennedy had seen notable drops in his support from as much as 15 percent to 5 percent recently, his departure did not have much impact on the big numbers from the forecast.

And more polling is needed to know what the effect could be in states where he was on the ballot, such as Michigan and Nevada.

Senate

The GOP remains the clear favorite to win back a majority in the Senate thanks to an advantageous map, though its chances have waned a bit. The party now has a 67 percent chance of winning the upper chamber, down from 78 percent before the forecast model went down, and is projected to win 51 seats.

“We can empirically say the switch from Biden to Harris has helped the Democrats’ chances at the presidential level, maybe a little bit at the Senate level,” Tranter said. “The Republicans are still certainly heavily favored.”

Republicans have been eager about their chances of winning the Senate this year, as Democrats are defending about a half dozen potentially vulnerable seats, while the GOP is defending arguably two at most. And both of those seats are still favorable for Republicans.

But most of the key races in states that are battlegrounds — such as Pennsylvania, Wisconsin and Nevada — either are toss-ups or slightly favor Democrats, who have pointed to strong incumbents as the reason for their current position.

Still, the realities of the map keep the GOP in a good position despite the strong Democratic candidates.

Republicans are almost certain to pick up a seat in West Virginia and are favored in Montana, where they are seeking to oust Sen. Jon Tester (D). Republican Tim Sheehy, who is running against Tester, has a 73 percent chance of winning, which is still only in the “lean” territory, but is a heavier tilt toward the GOP than other competitive Senate races.

Some polls have shown Sheehy ahead, unlike the Republican candidates in other states, and he has kept pace with Tester in fundraising.

“Montana, fundamentally, is a Republican state,” Tranter said. “And so, Tester obviously won it in 2018, so he’s got a history of winning a Republican state, but the polling is coming around on Sheehy.”

The chances of Republicans winning as many as 55 seats, as some would have hoped, seem dimmer, however.

House

Republicans currently have a 56 percent chance of winning the House, slightly down from the 61 percent odds they held before Biden dropped out — which is still a welcome sign for the GOP due to it maintaining a slight edge, but also one that gives Democrats some hope ahead of November.

Democrats need to net at least four seats to take control of the House in November, a task they are hopeful they can achieve amid the enthusiasm over Harris and the centrality of reproductive rights this cycle.

Republicans, meanwhile, are confident they will keep — and grow — their majority in the chamber, a belief buoyed by the concern over issues such as immigration and the economy.

Republicans currently control 220 seats in the chamber, while Democrats have 211. There are also four vacancies. The House GOP conference can only afford to lose four members on party-line votes when there is full attendance in the chamber.

Yet control of the chamber remains up for grabs. Tranter described the race for the House as “a roller coaster.”

“So many of these races are toss-ups,” Tranter said, adding, “And if four or five of these toss-up races start leaning Democratic or Republican, that can really change the probability a lot. That’s how close the House is.”

“I can’t stress enough: I would not be surprised if that flips 10 percentage points, probability-wise, in the next month,” he added. “That’s how razor-close that one is.”

DDHQ currently projects Republicans will hold at least 215 seats, and Democrats will win 210, with the remainder in the toss-up category, most of which lean toward the GOP. Cook Political Report, similarly, has 24 seats in the toss-up category.

But Tranter said fundraising and polling could alter that outlook in the final sprint to Election Day.

“There’s just so many toss-ups that one good fundraising quarter, a couple good polls — they’re all just on a razor’s edge right now, slightly favored to Republicans, but five or six of those races could easily move in the Democrats’ favor in the next month,” Tranter said.

While the House outlook is an improvement for Democrats from Biden’s time at the top of the ticket, the numbers have not shifted to the same level as Harris’s forecast for the presidential race. Tranter said stronger fundraising and other metrics for Republicans are holding up the party’s chances.

“The Republicans had a stronger fundraising quarter than they did previously. They caught up to the Democrats,” Tranter said, “so that’s what’s kind of propping them up a little bit.”