2024 election updates: Trump and Harris bring their campaigns to the battleground state of Wisconsin

Fencing has been installed ahead of Harris' speech at the Ellipse in Washington.

A new permit issued to the Harris campaign says up to 40,000 people are expected to attend.

The event, for which gates open at 3 p.m. ET, has been advertised to Harris supporters with push alerts, emails and online ads.

The Secret Service said in a statement to ABC News that it is "working closely with our federal and local partners to ensure the safety and security of Vice President Harris and all attendees at the campaign event on Tuesday at the White House Ellipse.

Several protest groups have announced plans to protest Harris' speech, including a large group of anti-war and pro-Palestinian protesters from several well known Washington-based groups.

According to the California Secretary of State, around 4.2 million mail-in ballots have been accepted by county registrar's offices. In other words, 21% of all of California's 22.8 million registered voters have already cast their ballots.

That percentage varies depending on the county. In Los Angeles County, 13% of registered voters' ballots have been accepted. In Ventura and Orange counties, the number is much higher - almost 22%.

The number of mail-in votes reached record-highs back in the 2020 presidential election, when 86.7% of Californians voted by mail. In total, 80.7% of registered voters cast ballots in the November 2020 contest.

MORE | How many Californians have already voted in the 2024 election?

You can't miss their ads on T.V. and radio. Candidates for a handful of congressional seats seem to be dominating the airwaves in recent weeks. Here's a closer look on why so much money is being spent on so few races.

Campaigning in Michigan, Sen. JD Vance was asked if, given Elon Musk's involvement in Trump's campaign, a Trump administration would give preferential treatment to Musk's Tesla over Detroit's Big Three automakers -- General Motors, Ford Motor Company and Stellantis.

Vance said no.

Since 2008, Saginaw County and Michigan have voted for the person who would win the presidential election. Asked by local reporters how important carrying Saginaw County and Michigan is for a path to 270 electoral votes, Vance said it was "extremely important."

"Michigan is one of, if not the very most important battleground state," Vance said.

Michigan is home to thousands of Big Three employees.

A set of state polls by CNN and SSRS released Tuesday found Trump and Harris to be effectively tied among likely voters in Arizona and Nevada.

The Democratic Senate candidates, meanwhile, comfortably lead in each state.

In the Senate race in Arizona, Democratic Rep. Ruben Gallego faces Republican Kari Lake. Lake is a Trump ally who was one of the most vocal election deniers after the 2020 election, refusing to concede that Trump had lost the presidential election and that she had lost her governor's race.

In Nevada, Democratic incumbent Jacky Rosen races Republican candidate Sam Brown.