Senate Majority Leader Mitch McConnell (R-Ky.) on July 21. Photo: Tasos Katopodis/Getty Images

Cook Political Report on Thursday moved its outlook to a net gain of five to seven Senate seats for Democrats, and now says Democrats are slightly favored to win the Senate majority. 

Why it matters: Cook currently forecasts that President Trump's troubles could affect Republicans down the ballot, calling the incumbent president the "decided underdog against former Vice President Joe Biden."

The state of play: Democrats must win at least four Senate seats to claim the majority.

  • Cook moved the race in Arizona between Sen. Martha McSally (R) and former astronaut Mark Kelly (D) from "toss up" to leaning Democratic in its July rating.
  • It also moved the races in Iowa between Sen. Joni Ernst (R) and Theresa Greenfield (D) and Georgia between Sen. David Perdue and Jon Ossoff from leaning Republican to toss-ups.
  • It moved Minnesota's and New Mexico's races from likely Democratic to solidly Democratic.

The big picture: Cook also shifted its outlook for 20 House races toward Democrats last week, signaling that Democrats stand to widen their lead in the House.

  • Republicans need to pick up 18 seats to win the House back in 2020, but polling is firmly moving against that hope.
  • Meanwhile, Trump is trailing Biden in multiple state polls less than four months before November's election.

Go deeper: Poll shows Biden beating Trump by 13 points in Florida

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Axios-SurveyMonkey poll: Harris boosting Biden ticket with key voters

Data: SurveyMonkey poll of 2,847 U.S. adults conducted Aug. 11–12, 2020 with ±3% margin of error; Chart: Naema Ahmed/Axios

Kamala Harris is accomplishing what Joe Biden's campaign hoped she would in her first two days as his running mate — doing no harm, while exciting parts of the base with whom Biden needs the most help.

The big picture: Black women especially, but also Black men, Hispanics and Democrats and independents across the board say they are more likely to vote for Biden with Harris on the ticket, according to a new Axios-SurveyMonkey poll.

McConnell announces Senate will adjourn until Sept. 8

Photo: Nicholas Kamm/AFP/Getty Images

Senate Majority Leader Mitch McConnell (R-Ky.) announced Thursday that the Senate will not hold any more votes until Sept. 8, though members will remain on 24-hour notice in case a coronavirus stimulus deal is reached.

Why it matters: With millions of Americans unemployed, the Trump administration and Democrats remain hopelessly deadlocked and unlikely to reach a deal any time soon.

Biden running mate news triggers "best grassroots fundraising day ever"

Former Vice President Joe Biden and Sen. Kamala Harris hug during a March campaign rally in Detroit. Photo: Scott Olson/Getty Images

More than $10.8 million was donated in four hours after Sen. Kamala Harris was announced as presumptive Democratic presidential nominee Joe Biden's running mate Tuesday, the Democrats' main donation-processing platform ActBlue said, per the New York Times.

Why it matters: Biden is lagging behind in fundraising to President Trump, whose campaign and the Republican National Committee out-raised that of the Democrats' last month. But Biden's announcement triggered his campaign's "best fund-raising hour," his deputy digital director, Clarke Humphrey tweeted, adding it was the campaign's "best grassroots fundraising day ever." ActBlue took $2.3 million in donations during the same hours of 4pm to 8pm Monday, "suggesting a bump as large as $8.5 million" for Biden, the Times notes.

Go deeper: Political world reacts to Biden tapping Kamala Harris as running mate