Republicans will win a "bare majority" to take over the Senate this fall, Sen. Rob PortmanRobert (Rob) Jones PortmanTax rules will be subject to more OMB review under new memo Ending sex trafficking tomorrow requires preventing child abuse today Doctors bristle at push for opioid prescription limits MORE (R-Ohio) predicted Friday.

Republicans need to gain six seats to win a Senate majority for the first time since 2006, and are widely favored to win three seats in West Virginia, South Dakota and Montana.

The party is optimistic it will win another three states and will not see any of its incumbents lose.

“Well, I think at the end of the day, I think it will be — it will be a bare majority," Portman said Monday on Fox News's "America's Newsroom."

"But I do think the chances are that we do get the majority,’’ said Portman, who serves as the National Senatorial Campaign Committee's vice chairman for finance.

Portman said he thinks his party has the upper hand because the public thinks the country is headed in the wrong direction and because the party has some “awfully good” candidates running this year.

Portman said seven Senate Democrats are vulnerable not only because they're up for reelection in red states, but in states Mitt Romney won in the 2012 presidential election.

“In six of those states, President Obama got less than 42 percent of the vote. So, this year, the math and the map tend to work for the Republicans,” he said.

Portman, who is up for reelection to the Senate in 2016, was also asked about running for president.

“I'm up for reelection in the Senate that same year, and that's what I'm planning to do. However, I have said consistently that, look, I do think the country's in trouble. I think we're in trouble in terms of the lack of opportunity and hope. I think we need someone who can bring this country together, as we talked earlier,” he said. “And so, you know, I'll see who steps up. I think the Republican Party needs someone who is going to take that broader approach and ensure that people understand that our policies for economic growth, for getting America back on track, affect every family in America.”

The Republican National Committee announced last week that Cleveland, in Portman’s home state, will host the 2016 Republican National Convention that summer.