The nomination on Wednesday of Judge Merrick Garland for the Supreme Court kicked off a new phase in the aggressive advocacy campaigns from liberal and conservative groups aiming to advance, or block, President Obama’s choice to fill the empty seat at the high court.

The choice of Garland drew widespread praise from civil rights and left-leaning interest groups, while intensifying opposition from conservatives who argue the next president should nominate the replacement for Justice Antonin Scalia, who died last month.

Until Wednesday, the advocacy campaigns had primarily focused on process rather than individual nominees. Liberal groups argued that Senate Republicans, in refusing to consider any Supreme Court candidate, were violating their constitutional duty. Conservative groups, meanwhile, mobilized to support Senate Majority Leader Mitch McConnell’s strategy to ignore any nominee.

“Now that we have a name and a face, we think that this campaign will really soar,” said Wade Henderson, president of the Leadership Conference on Civil and Human Rights.

The conference is working with dozens of lawyers’ and civil rights groups — including the Lawyers Committee on Civil Rights Under Law, NAACP Legal Defense and Educational Fund, Alliance for Justice and People for the American Way — to promote Garland’s record and try to build pressure for at least a hearing on his nomination.

The progressive grassroots group plans to hold about 50 rallies outside senators’ offices in the coming days to demand hearings.

Emily’s List, which backs Democratic women candidates, praised Garland and directed its criticism at Republican senators facing tough re-election battles this year — Kelly Ayotte (N.H.), Richard Burr (N.C.), Mark Kirk (Ill.), John McCain (Ariz.) and Pat Toomey (R-Pa.) — urging them to support nomination hearings.

Conservative groups, which for weeks had been compiling research on potential nominees and airing ads supporting the Senate Republican blockade, began attacking Garland’s record on Wednesday.

The announcement ceremony in the White House Rose Garden had yet to wrap up when the Judicial Crisis Network, a conservative legal group, began circulating a lengthy list of Garland’s decisions on past cases that they view as solidly liberal.

JCN plans to launch a new seven-figure advertising campaign opposing his confirmation, the details of which will be released soon, said the group’s chief counsel, Carrie Severino.

JCN previously launched two major ad buys — a seven-figure television, radio and digital campaign targeting Senate Republicans, and a six-figure ad buy targeting Democrats. It also hired a team of 10 opposition researchers associated with America Rising Squared.

“We’ve done a good deal of research on Judge Garland so far and now we’re in the midst of a big surge to get after the record to make sure the American people have all the information they need to weigh this debate,” said Brian Rogers, executive director of America Rising Squared.

Their initial criticism focused on Garland’s decisions in two cases involving gun laws. In one, while on the D.C. Circuit Court of Appeals, Garland voted in 2007 to reconsider a case, D.C. v. Heller, in which a panel of judges had ruled to invalidate a D.C. handgun ban. The Supreme Court later affirmed the panel’s decision, overturning the ban in a win for gun rights advocates. Scalia wrote the majority opinion, which conservatives consider one of the most important he authored.

Other conservative groups remained steadfast in their argument that no nominee should be considered until the next president is elected.

“This debate is over the process, not the nominee,” said FreedomWorks chief executive Adam Brandon. “Our community of conservative activists believes that Majority Leader McConnell and Chairman Grassley should stand firm and continue to insist that they will not hold hearings or a vote on the nominee until the next president is sworn into office.”

Many civil rights and womens groups were excited about the prospect of Obama nominating a minority or woman. On Wednesday, most held back on criticizing the choice of Garland and instead criticized Republicans for vowing not to consider any nominee.

“We were very gratified the president was considering a number of exciting nominees who would have brought greater diversity to the bench,” said Sherrilyn Ifill, president of the NAACP Legal Defense and Educational Fund. “We’re very pleased those names were on the short list and were given careful consideration. We also recognize that we are in a very particular political moment created by those in the Senate who have announced their intention not to do their job.”

Among other judges considered for the nomination were Sri Srinivasan, who would have been the first Asian American justice; Paul Watford, a black judge on the U.S. 9th Circuit Court of Appeals; Iowa appellate judge Jane Kelly; and Ketanji Brown Jackson, a black female judge on the U.S. District Court for the District of Columbia.

Garland is viewed by many as more of a consensus nominee — who perhaps would receive a less hostile reception from Senate Republicans — than the two other finalists. At 63, he is older than Srinivasan and Watford, both in their 40s, and has previously drawn praise from many of the same Senate Republicans now vowing to block the chamber’s consideration of any nominee.

Henderson defended the choice of Garland by noting that Obama has diversified the federal bench significantly.

“We all have preferences and candidates we might have liked to have seen, but the president has chosen someone who is superbly well qualified,” he said. “We’re fully behind the president and his decision.”