Democrats began laying out an aggressive strategy Thursday to get Judge Merrick Garland considered by the Senate and seated on the Supreme Court, over what appears to be implacable Republican opposition.

The approach, which is being implemented in part by a well-organized group led by former aides to President Obama, involves targeting vulnerable GOP Senate incumbents for defeat by portraying them as unwilling to fulfill the basic duties of their office. The idea is to so threaten the Republicans’ Senate majority that party leaders will reconsider blocking hearings on Garland’s nomination.

“You’re going to be surprised at how hard we’re going to work to make sure this is on the front pages of all the papers,” Senate Minority Leader Harry M. Reid (D-Nev.) told reporters after meeting with Garland on Thursday.

At the White House, Obama held a conference call with thousands of supporters across the country while senior adviser Valerie Jarrett met on Capitol Hill with members of the Congressional Black Caucus. White House press secretary Josh Earnest told reporters he had no details of a specific request Obama was making on the call. “But I think the president sent a pretty clear signal, though, that this a high priority of his, and he hoped that this would be a priority that people all across the country would share,” he said.

Before Garland arrived on Capitol Hill for the first time as Obama’s nominee, Senate Democrats rallied in front of the Supreme Court to denounce Republican refusal to consider the nomination. Elsewhere in Washington, advocates on both sides readied for clashes across the country, but focused on states represented by GOP senators up for reelection in November.

Speaking after President Obama announced Merrick Garland as his nominee to the Supreme Court March 16, Senate Majority Leader Mitch McConnell said "the American people should have a say in the court's direction." (Reuters)

Democrats acknowledged that Republican opposition will be slow to crumble.

Senate Majority Leader Mitch McConnell (R-Ky.), briefly addressing the standoff in a floor speech Thursday, insisted there would be no faltering.

“When it comes to filling the current Supreme Court vacancy, which could fundamentally alter the direction of the court for a generation, Republicans and Democrats simply disagree,” he said. “Republicans think that the people deserve a voice in this critical decision; the president does not. . . . As a result, we logically act as a check and balance.”

Several additional Republican senators said Thursday that they would grant Garland a courtesy meeting when the Senate returns after a two-week recess that begins Friday. In every case, however, they insisted that such a meeting would not change their position on hearings for Garland.

“I’ll meet with the guy, but trust me: We’re not going to let the Supreme Court flip,” said Sen. Ron Johnson (Wis.). “And this nominee obviously would flip the court, particularly on an issue that is pretty important in Wisconsin — the right to keep and bear arms.”

Johnson faces what is expected to be a close reelection race this year against former Democratic senator Russell Feingold, who received an endorsement Thursday from Obama.

Two other GOP senators, Bill Cassidy (La.) and Mike Rounds (S.D.), also said they would be open to a courtesy meeting but would not change their minds on the election-year blockade of the nominee.

Everything you need to know about appointing a Supreme Court justice

Many GOP senators had previously said they would not meet with whomever Obama nominated, so Democrats saw the willingness to meet with Garland as evidence that Republicans are aware of the political optics of the situation. Democrats are embracing a slippery-slope theory that begins with courtesy meetings and ends in hearings and an eventual up-or-down vote on the nomination.

“It’s a step at a time,” said Sen. Charles E. Schumer (D-N.Y.). “A good number of them put their foot in the water yesterday by saying they’d see him. . . . There’ll be more of those. The next step will be to have a hearing.”

In keeping with a long tradition, Garland did not address the controversy around his nomination during his visit on Capitol Hill. He huddled with Sen. Patrick J. Leahy (Vt.), the top Democrat on the Judiciary Committee, for less than 20 minutes in Leahy’s office.

“What you see is what you get with him,” Leahy said. “There’s no hidden agenda.”

Garland left the meeting and headed down a hallway and out of sight, accompanied by several White House aides, led by senior adviser Brian Deese. Later in the day, he made a similarly discreet exit from Reid’s office.

“I just told him to be himself, to be calm and collected, and I think that’s his nature anyway,” Reid said. “I think he going to do just fine.”

Leahy, a veteran of more than a dozen Supreme Court confirmation battles, said the two did not discuss politics or any role Garland might play in trying to persuade Republicans to give him a chance. Leahy said he did tell Garland about “where the hurdles are” in the typical confirmation process.

But the process this time promises to be anything but typical. The GOP’s determination to keep the late Justice Antonin Scalia’s seat open for the next president to fill has already upended most of the usual customs, starting with the dust-up over courtesy meetings.

And where the Senate itself would typically take the lead role in vetting a Supreme Court nominee, there are no plans this time for the Judiciary Committee to hire its usual complement of additional staffers to conduct such checks. Beth Levine, a spokeswoman for the panel’s Republicans, confirmed Wednesday that there are no plans to hire additional investigators for a Garland probe.

That has given outside groups a central role in the coming fight, especially on the Republican side. Most prominent among them is the Judicial Crisis Network, which has coordinated the conservative response to the Scalia vacancy and has pledged to run millions of dollars in television ads to derail Obama’s nominee.

The group issued talking points Tuesday that said Garland would support “a laundry list of extreme liberal priorities, like gutting the Second Amendment, legalizing partial-birth abortion, and unleashing unaccountable bureaucratic agencies like the EPA and the IRS.”

America Rising Squared, a GOP-aligned opposition research organization, had been working with the Judicial Crisis Network and the Republican National Committee to investigate potential nominees. Brian Rogers, the firm’s executive director, said Wednesday that he now had about a dozen researchers digging into Garland’s background; some will be deployed across the country to vet the judge.

“The White House is planning a big coordinated effort, and we need to, too,” Rogers said.

The president’s mobilization call Thursday was organized by the Constitutional Responsibility Project, a nonprofit group formed by several former top Obama staffer. The group includes Stephanie Cutter, Julianna Smoot, Anita Dunn and Amy Brundage, all of whom worked both on his campaign team and in the White House.

The new tax-exempt organization, which is aimed at providing a platform for hundreds of groups to share information, has planned a series of events over the congressional recess, including a MoveOn Day of Action on Monday, with more than 50 grass-roots events outside senators’ offices, and a robust social-media campaign.

In Ohio, teachers will aim to put pressure on Sen. Rob Portman (R) with “Do Your Job Learn-ins” in Cleveland, Cincinnati and Lima. In Pittsburgh and Philadelphia, nurses, firefighters and union members will call on Sen. Patrick J. Toomey (R) to meet with Garland and hold a hearing on his nomination.

Democrats are piggybacking on the GOP line that the “people’s voice” will be heard, but they are betting that will happen before the election.

“I think you’re going to start seeing the public asking and asking and asking why there isn’t a hearing,” said Sen. Amy Klobuchar (D-Minn.), a Judiciary Committee member. “I think you’re also going to see, once you meet with the nominee . . . you think: ‘Well, at least we should have a hearing.’ But what I really think is going to change their mind is their own constituents.”

Karoun Demirjian and Kelsey Snell contributed to this report.