Senate Judiciary Committee Chairman Charles E. Grassley (R-Iowa) has a major say on whether President Obama's nominee to the Supreme Court will get a hearing. (J. Scott Applewhite/AP)

When President Obama sought bipartisan cooperation on his first major legislative endeavor — passing his signature health-care law — he set his sights on one man: Sen. Charles E. Grassley of Iowa, then the top Republican on the Senate Finance Committee.

Despite months of entreaties, Grassley never came around on the Affordable Care Act, which ended up passing in the Senate on a series of party-line votes. Now, six years later, Grassley again occupies a central role in what is possibly Obama’s last big fight with Congress.

As chairman of the Senate Judiciary Committee, Grassley wields the power to hold hearings and advance Obama’s promised Supreme Court nominee through the confirmation process. He is in lock step with Senate Majority Leader Mitch McConnell (R-Ky.), who declared in the hours after the Feb. 13 announcement of Supreme Court Justice Antonin Scalia’s death that the next president, not Obama, would name his successor.

But key Democrats think Grassley can be persuaded — or, more precisely, shamed — to take up an Obama nomination in the coming months, thus breaking the Republican blockade and opening the door to an eventual confirmation vote.

Four cases that could re-shape the country will be heard when the Supreme Court meets this term without Justice Antonin Scalia. Scalia consistently expressed conservative views when reviewing court cases. (Claritza Jimenez/The Washington Post)

Senate Minority Leader Harry M. Reid (D-Nev.) launched an opening salvo at Grassley last week, accusing him in a floor speech of having “surrendered every pretense of independence” and having allowed McConnell to “annex the Judiciary Committee into a narrow, partisan mission of obstruction and gridlock.”

“Is this the legacy he wants?” Reid said. “Is this how he wants his committee work remembered — as a chairman who refused his duty and instead allowed the Republican leader to ride roughshod over the Judiciary Committee’s storied history?”

Grassley responded tersely the following day in a floor speech of his own: “We all know that is how some people act when they don’t get their own way, but childish tantrums are not appropriate for the Senate.”

Obama personally made his case for action Tuesday morning, when McConnell and Grassley visited the White House to discuss the Supreme Court vacancy. Vice President Biden and Sen. Patrick J. Leahy of Vermont, the senior Judiciary Committee Democrat, also attended the closed-door meeting.

Grassley said after that he remained opposed to taking up Obama’s nominee: “Whether everybody in the meeting today wanted to admit it, we all know that considering a nomination in the middle of a heated presidential campaign is bad for the nominee, bad for the court, bad for the process and, ultimately, bad for the nation.”

Although Obama did not confront Grassley as directly as Reid has — it was McConnell who did most of the talking Tuesday, a person familiar with the meeting said — Democratic lawmakers and aides said they think that the 82-year-old sixth-term senator will be forced to relent.

During the health-care battle, Obama tried to cajole Grassley into supporting the bill by making a series of changes. In an interview with the Los Angeles Times last month, Obama described working with an unnamed Republican on the sprawling legislation, having “taken every idea that he had ­suggested.”

“He just finally turned to me — I was sitting in the Oval Office — and he said, ‘You know what, Mr. President, I got to admit there’s no change that allows me to vote for this thing,’ ” Obama said.

An individual familiar with the exchange who spoke on the condition of anonymity to discuss private conversations confirmed that Obama was speaking about ­Grassley.

Where the White House previously tried to win Grassley over with carrots, the Supreme Court fight has Democrats turning to sticks — arguing that the court blockade will undermine Grassley’s legacy and his carefully tended just-folks image.

Reid again targeted Grassley in floor remarks Monday, saying that “history will not be kind to his tenure as chairman” if the blockade continues.

“The chairman has turned the impartial reputation of the Judiciary Committee into an extension of the Trump campaign,” Reid said, before noting Grassley’s attendance at a January rally for Donald Trump’s presidential bid in Pella, Iowa.

He also took aim at Grassley’s record streak of consecutive Senate votes cast — more than 7,500 dating to July 1993 — saying the Supreme Court blockade “taints” that distinction: “What good are 7,500 consecutive votes if you simply sweep the votes you don’t like to take under the rug?”

In a brief interview Monday, Grassley brushed off Reid’s remarks: “I ain’t going to hold it against him. It’s one of these things where today we disagree on something and tomorrow we’ll agree on it. That’s just the collegiality of the Senate.”

Democrats have gotten some support in their efforts to paint Grassley as an obstructionist — if not a hypocrite — from voices in the six-term senator’s home state.

At least a half-dozen Iowa newspapers have called on the Senate to consider Obama’s Supreme Court nominee, including the state’s largest, the Des Moines Register.

“This was an opportunity for our senior senator to be less of a politician and more of a statesman,” the paper wrote. “[B]ut he chose instead to disregard his constitutional duty by rejecting a nominee who hasn’t even been named.”

A particularly sharp editorial came from the Hawk Eye in Burlington, Iowa, a paper that heralded Grassley’s record-breaking consecutive vote in January. Last week, citing Grassley’s “smug, partisan rhetoric,” the paper declared, “We take it back.”

Grassley said he was not concerned about the editorials or other feedback he has gotten from Iowans on the high-court vacancy. “You can’t worry about those things, so don’t even ask me about whether or not I’m worried about reelection,” he said.

Should the White House determine that Grassley is the most crucial figure in breaking the blockade, one particular nominee could bring special pressure to bear: Judge Jane L. Kelly of the U.S. Court of Appeals for the 8th Circuit was unanimously confirmed by the Senate in 2013 after serving as a federal public defender in Iowa for the previous two decades.

Kelly — who graduated from Harvard Law School in 1991, the same year as Obama — first applied for the 8th Circuit seat to then-Sen. Tom Harkin (D-Iowa), according to a questionnaire from her Senate confirmation hearing. But Grassley spoke highly of her at the hearing.

Grassley read portions of a letter of support from former 8th Circuit judge David R. Hansen, for whom Kelly had clerked in the early 1990s.

“Every sentence of it speaks highly of your work,’’ Grassley said.

Democrats said they are confident that McConnell and Grassley will hold hearings.

But several Republican senators said they expected Grassley would hold fast.

“Do you know Chuck Grassley?” Sen. David Perdue (R-Ga.), a Judiciary Committee member, asked a reporter. “When he gets on a principle, he’s like a bulldog with a bone. He’s going to stay on that principle.”

Juliet Eilperin and Jerry Markon contributed to this report.