Early voting for Florida's primary starts Monday, and Tampa Bay-area Democrats and Republicans have kicked off their strategies for the upcoming election.

  • Sen. Marco Rubio campaigned in Tampa Bay area Saturday
  • Campaigns are already focusing on battleground state
  • Florida has 400,000 new registered voters

To prepare, the GOP opened a new campaign office in Brandon. Sen. Marco Rubio was on hand for the grand opening, where he encouraged staff, volunteers and voters from across the country to support Republican candidates in the general election.

Rubio is currently running in a tight race to keep his Senate seat.

"I'm the only one running for U.S. Senate in Florida that if need be will be a check-and-balance on the next president of the United States no matter who that is,” Rubio said. “My Democratic opponent, Patrick Murphy, is going to be a rubber stamp if, God forbid, Hillary gets elected.”

As Rubio met with voters, he acknowledged the battle between Donald Trump and establishment Republicans. Rubio and Trump were bitter rivals in the primary but have since endorsed each other.

"At this point, the choice we have is between Hillary Clinton and Donald," Rubio said. "As I've said before, I do disagree with Donald on a number of issues, but I disagree with Hillary on every issue, and that's the choice before me. People will have to make their own choice."

Despite harsh criticism from Trump’s recent comments, Rubio said he doesn’t think his party is divided or that supporting the GOP nominee is hurting his campaign.

"The presidential race is an election for president. I think people understand that the Senate is an independent branch of government. It's a co-equal branch. Senators don't work for the president, they work for the people of the states that elected them," Rubio said.

Rubio said he’ll continue to keep his focus on winning in November and maintain the critical majority in the Senate. 

During the outing, he also made stops in Polk and Osceola counties.

On the other side of the aisle, the South St. Petersburg Democratic Club also met Saturday to discuss their "Get Out and Vote" strategy. Florida has never had more registered voters going into the August primary than it does now.

A surge of almost 400,000 new voters are ready to cast ballots this election cycle. Republicans have the edge with new voters; 59 percent have registered as Republican.