Senate Minority Leader Mitch McConnell predicted big Republican gains in the midterm elections and expressed hope that President Barack Obama would respond to a voter rebuke by shifting his agenda and compromising with the GOP on policies to reduce government spending and shrink the national debt.

During a 30-minute interview in his Capitol office, the Kentucky Republican cautioned his party against overconfidence, warning that a GOP rout was far from certain against Democratic opponents he described as smart, tough and better-financed. Perhaps aware that voters’ expectations of Republicans could rise after the midterms commensurate with the number of seats they win, McConnell downplayed what the GOP might be able to accomplish legislatively absent a cooperative Obama.

“He is the president, and I think it’s important not to overstate what’s possible — to be honest with the American people, that changing the Congress doesn’t entirely change the government. But it might help change the president’s mind and change the president’s direction,” McConnell said Thursday. “The president’s a smart guy; he certainly wants to have a second term. I don’t think he’s going to ignore the wishes of the American people any longer, and so I’m optimistic.”

“He’s tried it his way, we’re going to have a referendum on his way, and hopefully he will have the flexibility to go in a different direction after Nov. 2,” McConnell added. “I want to sum it up this way: I don’t want the president to fail. I want the president to change.”

With a divisive GOP primary season over, the former National Republican Senatorial Committee chairman discussed the Senate playing field with a political tactician’s precision. He dismissed Republican infighting during the primaries as irrelevant to GOP performance in the general election, saying the tea party movement of conservative activists has been a net positive in helping to reinvigorate a party that was flat-lining less than two years ago.

Ticking off the Senate playing field state by state, McConnell projected that Republicans would retain GOP-held open seats in Florida, Kentucky, Missouri, New Hampshire and Ohio. The 68-year-old Minority Leader also confidently predicted that no Republican Senator would lose in November, a far cry from where his Conference stood at the precipice of the 2006 and 2008 elections, which resulted in a net loss of 14 seats.

Additionally, McConnell described the races for the following Democratic-held seats as those where his party is either competitive or polling head and “has a legitimate shot”: Arkansas, California, Colorado, Connecticut, Delaware, Illinois, Indiana, Nevada, North Dakota, Pennsylvania, Washington, West Virginia and Wisconsin. Democrats argue Republicans are overestimating their prospects, particularly after last week, when tea party favorite Christine O’Donnell upset Rep. Mike Castle in Delaware’s GOP Senate primary.

“The environment for us is excellent. The wind is at our back, the primaries are out of the way and a second wave of the hurricane is about to hit on Nov. 2,” McConnell said. “I think I’m going to be the leader of a larger group after November, but that’s about as far as I’m going to go on the prognostication front.”

Senate Republicans need to win 10 seats to capture the majority. On the House side, the GOP’s magic number is 39.

McConnell, the Senate Republican leader since 2007, said his top priority at the beginning of this election cycle was “honing” a GOP message that would simultaneously unite the Conference and garner the support of the American public while drawing a stark contrast with Obama and the Democratic majority.

McConnell credited his leadership team and rank-and-file Members with the achievement of this goal, which the Kentuckian said is evidenced by the mountain of public polling showing the GOP positioned to pick up several Senate seats this fall. The party suffered major legislative defeats, including on the $800 billion stimulus bill, the health care overhaul and financial regulatory reform, and that is why McConnell said his No. 2 priority was to grow his caucus.

“In addition to helping craft the message and unify the Conference so we could have that national debate,” McConnell said, there was the question of helping NRSC Chairman John Cornyn (Texas), “who’s done a spectacular job of candidate recruitment and fundraising and all the rest, to give every spare moment I could — outside of when I’m here — to the NRSC,” said McConnell, who led the NRSC during the 1998 and 2000 cycles.

McConnell said he’s traveled to 20 states in the past 18 months and had a hand in every aspect of the campaign, including fundraising and candidate recruitment. According to statistics provided by his office, he has attended more than 250 events for Republican candidates this cycle — sometimes hitting two or three fundraisers per night after a full day of legislative business — and raised $4.7 million for the NRSC, including $2.9 million this year.

Not all quarters of the Republican base are pleased with the decisions he and Cornyn have made in terms of candidate recruitment and resource allocation. Led by Sen. Jim DeMint (R-S.C.) on Capitol Hill and some segments of the tea party movement around the country, some conservative activists have taken issue with the NRSC supporting Castle in Delaware and other Republican candidates they deemed too moderate.

McConnell dismissed suggestions that the GOP leadership, DeMint and those who follow him were not on the same page in the upcoming general elections, describing the South Carolina Senator as graciously having volunteered to take the lead in aiding O’Donnell in the First State.

The aspect more telling about where this election is headed was the main election message he said is being offered by Democrats — focused on demonizing Republicans rather than promoting their own accomplishments.

“They’ve got to have something to run against, and I guess they’ve, at least for the short term, chosen my buddy” House Minority Leader John Boehner (R-Ohio), “and maybe they’ll be after me next week,” McConnell said. “They don’t have much else.”