According to a press release, Booker's hired 270 Strategies to help build Booker's grassroots campaign. The firm is run by Mitch Stewart, who served as battleground states director in President Obama's 2012 campaign, and Jeremy Bird, who was Obama's national field director.

Bird and Stewart are joining another team that worked on Obama's presidential bid, Benenson Strategy Group, as a part of Booker's campaign.

Meanwhile, Rep. Frank Pallone, one of Booker's Democratic primary opponents, announced his campaign team, comprised of a number of New Jersey and national Democratic firms.

Pallone has hired Anzalone Liszt Research, a prominent Democratic pollster that has done work for the campaign committees and the President's campaign, as well as Crossroads Campaign Solutions, which worked on Sen. Robert MenendezRobert (Bob) MenendezLawmakers target horse meat trade Senators, staff get approval to testify in Menendez corruption trial Trump admin not opposed to new war authorization MORE's (D) reelection campaign.

He's also brought on Sean Darcy, former spokesman for New Jersey Govs. Richard Codey and Jon Corzine.

Booker is the heavy favorite in the Democratic primary, and whomever wins the nomination is favored to go on to keep the seat.

He'll face Reps. Pallone, Rush Holt and state Assembly Speaker Sheila Oliver in the Aug. 13 primary. The general election will be held on Oct. 16.

--This piece was updated at 4:55 p.m. to reflect details on Pallone's campaign.