Senate Majority Leader Mitch McConnell (R-Ky.) in an interview with The Hill said he thinks Republicans can make a play for Democratic Sen. Sherrod Brown's seat in Ohio.

Brown previously hadn't been a top target of McConnell's, who just last week left Ohio off a list of Democratic-held seats he saw as top midterm targets.

His new comments point to the growing optimism among Republicans that they can widen the map, and that their electoral prospects are improving with a strengthening economy and an uptick in President Trump's approval numbers.

"I saw a survey within the last week in Ohio indicating that race is very competitive. I would certainly add Ohio to the list," McConnell told The Hill.

A Republican strategist said internal polling shows the race between Brown and Rep. Jim Renacci (R-Ohio) is "within the margin of error."

"Within the past week a number of Republicans have been talking about it behind the scenes," said the GOP source. "The survey has given Republicans reason for hope. It's internal polling."

The strategist conceded that it would be difficult to defeat Brown, a two-term incumbent who is rumored to be a potential White House candidate in 2020, but argued it's looking more likely than before.

McConnell's growing confidence about the midterm election is fueled by what he says is the most productive record by a "right-of-center" Congress in more than 30 years.

"I'm now in my third decade in the Senate. This has been the best period, the best period right-of-center over the last 17 months, in the time that I've been here. It's been a period of extraordinary accomplishment," he said.

"We think we have made a very significant difference for the country in measurable ways," McConnell added. "Conveying that to the voters in places that we have Senate races is going to be a big part of being competitive."

McConnell said he wants Trump to do more to talk up the Congress's accomplishments, something GOP senators requested of the president during a recent meeting on Capitol Hill.

"I'd like the president to talk about it more often and I believe he will going into the fall campaign," he said.

He pointed to what Republicans say is the best economy in 18 years, last year's $1.5 trillion tax-reform package, increased spending for the military, 15 repealed regulations and the confirmation of a conservative Supreme Court justice and 21 conservative circuit court judges.

Republicans also opened the Arctic National Wildlife Refuge to oil drilling and repealed ObamaCare's individual mandate as part of tax reform.

In an interview with The Wall Street Journal this past week, McConnell identified six states as "legitimate pickup opportunities" - Montana, North Dakota, Missouri, Indiana, West Virginia and Florida. That left out Ohio and Pennsylvania, though he said those states could "get on the radar."

McConnell told The Washington Post earlier this month that the battle for the Senate will run through Arizona, Nevada, Tennessee, Montana, North Dakota, Missouri, Indiana, West Virginia and Florida.

The Post noted that Ohio, Pennsylvania and Wisconsin were absent from that list.

The source said Ohio Republican gubernatorial candidate Mike DeWine has a strong get-out-the-vote operation that will help "pull up other candidates down the ticket."

Democrats are projecting confidence in Ohio.

They note that Renacci has struggled to raise money from donors. He reported collecting $4.5 million as of mid April, including $4 million he loaned to his own campaign.

Even so, they expect the race to be close.

"It's an Ohio statewide election in a midterm year, of course it's competitive," said Preston Maddock, Brown's campaign spokesman.

Brown has been running television advertisements since last week defining Renacci.

"We're running against Jim Renacci, who has a unique amount of baggage," said Maddock. "We're drawing a contrast between Sherrod Brown, who fights for workers every day, and Renacci, who looks out for himself."

McConnell said he expects the GOP base to make up a bigger portion of the electorate in the midterms than in the 2016 presidential election and said Trump will be key to mobilizing conservative voters in red states.

"We know the base will probably be a more significant part of the election than in a presidential year, but that doesn't mean independent voters aren't important too," he said.

McConnell said "base voters are pretty dominant in places where we have a good chance of success," citing Montana, North Dakota, Missouri, Indiana and West Virginia.

Trump won all these states by double digits in 2016, ranging from a 42-point margin of victory in West Virginia to 19-point wins in Missouri and Indiana.

He said Trump "indicated he's really willing to help," noting that the president visited Indiana two days after the primary and also has been in West Virginia.

"I think you're going to see him in all of these red states where his standing is quite high," he added.

McConnell conceded in a New York Times interview earlier this year that Senate Republicans had a "fundraising problem," referring to the money advantage the Democratic Senatorial Campaign Committee (DSCC) has accumulated over the National Republican Senatorial Committee (NRSC).

The DSCC has reported $32.3 million in cash on hand compared to the NRSC's $16.8 million.

Senate Democratic incumbents have also outraised their GOP challengers.

"The Democratic incumbents in red states are clearly benefiting from the energy on the left," McConnell noted, pointing to the $4 million Sen. Claire McCaskill (D-Mo.) raised during the first three months of the year.

But he told The Hill he's confident that outside GOP-allied groups will help make up the difference.

"When you consider the total firepower - candidates, campaign committees and super PACs - I don't think we'll lose a single race because we were swamped financially," he said. "I think the cumulative firepower on each side is likely to be in the end roughly equal."

McConnell also said he expects the Republican National Committee (RNC) to help.

Juston Johnson, the RNC political director, sparked grumbling among Senate Republicans last month when he declared that his "No. 1 priority is keeping the House" and that the committee crafted its budget on that basis.

McConnell, however, has made it clear to RNC officials that protecting the Senate GOP should be an equally high priority.

"I believe they'll be helpful to us," he said. "They're kind of the marquee committee of the campaign committees on our side and they've done an absolutely spectacular job during the Trump administration."

"I've talked to them about it. Everybody understands if you lose the Senate, the president will be knee-capped the last two years of his term when it comes to appointments," he said.

The RNC has $43.8 million in cash on hand, according to its last fundraising report, significantly more than the $8.7 million reported by the Democratic National Committee.