WASHINGTON >> When Joe Biden won the presidency, hopes rose that he might be the rare Democrat who could finally crack the code of Mitch McConnell and find bipartisan common ground based on their shared past as Senate deal-makers.

Nearly five months into Biden’s tenure, those aspirations have yet to materialize, and McConnell, the Republican leader, made plain last week that he had little interest in nurturing them, declaring himself to be “100% focused” on stopping Biden’s agenda.

With the top four congressional leaders scheduled Wednesday to gather for the first time with Biden at the White House, McConnell’s stance has only underscored the obstacles ahead. The senator has intensified his attacks on Biden’s legislative agenda, dismissing it as “go-it-alone radicalism” and criticizing the president for practicing “bait and switch” tactics — portraying himself as a moderate when, McConnell says, he is anything but. His office accuses the president of mixing “centrist words, liberal actions.”

McConnell made his “100%” remark — a comment that was quickly compared with his 2010 declaration that he was determined to make Barack Obama a one-term president — last week during a trip back home to Kentucky. Both comments were cited as evidence that the senator had zero interest in working with Democratic presidents to accomplish anything of substance, but was instead fixated on denying them accomplishments that could pay political benefits.

McConnell quickly sought to walk back last week’s comment, claiming that it was taken out of context, but the narrative was set.

With attempts to reach bipartisan deals on infrastructure, police conduct, safety net programs and more entering a critical phase, McConnell and Biden couldn’t be further apart, indicating that if the White House is to successfully reach across the aisle for agreements, it is much more likely to be with a small group of Republicans absent McConnell and most of the rest of his members.

“We have a good personal relationship, but I will not be supporting the kind of things they are doing so far,” McConnell said of Biden in a recent interview.

The White House was not particularly upset about McConnell’s remark, which Biden sought to play down. The president noted their previous success in striking deals to avoid fiscal calamity while he was serving as vice president, even as McConnell was dug in against the Obama White House.

“Look, he said that in our last administration with Barack — he was going to stop everything — and I was able to get a lot done with him,” Biden told reporters last week.

And privately, White House officials argue that McConnell’s position will help Democrats justify using procedural tools to force through legislation without Republican votes should that become necessary, as most expect it will.

They believe that McConnell’s rigid defiance sets up a winning contrast for Biden as he continues to profess openness to working with Republicans. If such bipartisanship proves impossible, the officials argue, Democrats need only to point to the minority leader’s own words to explain why.

“It is the same script we heard from McConnell for Obama,” said Sen. Richard Durbin of Illinois, the No. 2 Senate Democrat. “Barack is ‘one term.’ Now he is saying ‘100%.’ It is not encouraging.”

But the White House says it has not quite yet given up on McConnell and his colleagues. A White House adviser said today that Biden would use the meeting with leaders to try to identify areas where the two parties could work together on infrastructure, helping struggling middle-class families and maintaining competitiveness with international economic rivals. But the adviser also noted that doing nothing was not an option for the president.

Biden was one of the few Democrats who could claim to have had a productive and cordial relationship with McConnell, striking agreements with the Republican leader on tax and spending issues — even though some Democrats complained that the outcomes favored Republicans.

Their track record — and Biden’s stated focus on trying to restore the Senate’s lost tradition of bipartisanship — fed expectations that they could ease some of the Senate’s deep dysfunction and polarization. But most of that discussion took place when it appeared that Republicans would maintain control of the Senate, forcing an accommodation between a Democratic House and White House and a Republican Senate led by Biden’s old negotiating partner.

“One of the arguments I made last year was that the only way to guarantee Biden would be a moderate would be for me to be the majority leader of the Senate,” McConnell said. “And that didn’t work out, although it is close.”

Close, yes. But two upset Senate runoff wins by Democrats in Georgia in early January made Sen. Chuck Schumer, D-N.Y., the Senate floor leader by virtue of Vice President Kamala Harris’ power to break ties in the 50-50 chamber.

“The fact is we could do an infrastructure bill, we could do police reform,” said Sen. John Cornyn, R-Texas. “There are a number of things we could do if the administration wants to work with us. But so far, all the evidence is they don’t really want to work with us.”

But Democrats note that Republicans have refused to entertain proposals of the scope they argue is needed for the economy to regain its prepandemic form and to help American families and workers recover. Once again, they say, McConnell and his congressional colleagues are intent on stymying Biden and congressional Democrats to gain advantage in next year’s midterm elections.

They point to the difference between the $568 billion infrastructure plan offered by Republicans and the wide-ranging, two-part $4 trillion proposal from Biden paid for through corporate tax increases — a proposal Republicans refuse to consider — as evidence that the GOP is not serious about striking deals in the interests of the country.

As he sought to reframe his 100% comment from the blanket opposition it suggested, McConnell said that his desire to thwart the Biden agenda was dependent “on what it is.”

At the moment, that agenda is far beyond anything McConnell could ever bring himself to support, even from a president with whom he once had a strong working relationship.