WASHINGTON — Congressional Republicans lauded President Donald Trump’s decision Monday to nominate Brett Kavanaugh to replace Justice Anthony Kennedy on the Supreme Court as most Democrats fiercely slammed the pick — and potential GOP swing votes offered measured reactions.

In a statement, Senate Majority Leader Mitch McConnell, R-Ky., called Kavanaugh “a superb choice” and “extremely qualified” to serve on the high court. Sen. Chuck Grassley, R-Iowa, the Judiciary Committee chairman, said Kavanaugh is “one of the most qualified Supreme Court nominees to come before the Senate.”

A George W. Bush appointee, Kavanaugh, 53, has served as a judge on the U.S. Court of Appeals for the District of Columbia Circuit since 2006.

Republican Sens. Susan Collins of Maine, center, and Lisa Murkowski of Alaska, left, in Washington on March 21. J. Scott Applewhite / AP file

Roughly 30 GOP senators planned to attend the president's prime-time announcement in the White House East Room, Senate Majority Whip John Cornyn, R-Texas, told reporters earlier in the day.

Sen. Dianne Feinstein of California, the top Democrat on the Senate Judiciary Committee, and several key red state Senate Democrats had been invited to the White House for the event, but declined.

Two GOP senators who had been viewed as potential no votes on Kavanaugh — Susan Collins of Maine and Lisa Murkowski of Alaska — also turned down White House invitations to attend the announcement. Collins later released a measured statement praising Kavanaugh's "impressive credentials and extensive experience" without expressing support for the nomination.

"I will conduct a careful, thorough vetting of the president’s nominee to the Supreme Court, as I have done with the five previous Supreme Court Justices whom I have considered," Collins said in a statement provided to NBC. "I look forward to Judge Kavanaugh’s public hearing before the Senate Judiciary Committee and to questioning him in a meeting in my office."

Murkowski also issued a careful statement vowing a “rigorous and exacting” review of Kavanaugh’s record.

Sen. Rand Paul, R-Ky., who doesn't always follow his party's leaders, tweeted, "I look forward to the upcoming hearings, reviewing the record, and meeting personally with Judge Kavanaugh, with an open mind."

Some red state Democrats who declined the White House's invitation expressed similar sentiments.

Sen. Joe Donnelly, D-Ind., said in a statement that he declined "so that I can meet first with the nominee in a setting where we can discuss his or her experience and perspectives."

Donnelly was among three Democrats who voted with Republicans in April 2017 to confirm Neil Gorsuch as Trump’s first Supreme Court justice nominee in a 54-45 vote. The other two Democrats who defected were Sens. Heidi Heitkamp of North Dakota and Joe Manchin of West Virginia, who both face tough re-election races in November’s midterm elections. Heitkamp and Manchin were also invited Monday but declined, as did Sen. Doug Jones, D-Ala., who was sworn into the Senate in January.

McConnell has said that Congress will vote this fall on the nominee’s confirmation, but no hearing by the Senate Judiciary Committee has been scheduled yet. Confirming Kavanaugh will require the Judiciary Committee to report his nomination out favorably and 51 votes of approval in the full Senate. Because Sen. John McCain, R-Ariz., is expected not to vote as he battles brain cancer, Republicans can’t afford to lose a single vote, though Vice President Mike Pence could break a tie.

Kavanaugh said Monday night that he plans to begin meeting with senators on Tuesday, and said he will convey his view that he believes in an “independent judiciary,” which he described as “the crown jewel of our constitutional republic.” He said he will keep an “open mind in every case.”

When Kennedy announced last month his plan to retire, Democrats immediately demanded that Republicans hold off on considering the nominee until after the midterms this fall, using the same argument the GOP had when it refused to consider President Obama’s high court nominee Merrick Garland in 2016: that the person to fill the seat left vacant by the late Justice Antonin Scalia should be determined by voters in the election.

Sen. Bob Casey, D-Pa., came out early Monday morning against any Supreme Court nominee supported by the Heritage Foundation, which included all of the rumored contenders. McConnell later criticized Democrats on the Senate floor Monday afternoon who pre-emptively opposed the nominee ahead of the announcement.

Meanwhile, Senate Minority Leader Chuck Schumer, D-N.Y., called earlier in the day for the nominee to share his or her personal views on issues such as Roe v. Wade and health care. In a statement released immediately following Trump’s announcement, Schumer said: “I will oppose Judge Kavanaugh’s nomination with everything I have, and I hope a bipartisan majority will do the same. ... In selecting Judge Brett Kavanaugh for the Supreme Court, President Trump has put reproductive rights and freedoms and health care protections for millions of Americans on the judicial chopping block.”

Cornyn told reporters earlier in the day that Schumer was unlikely to get the information he was looking for. “I think it’s a pipe dream of my friend, Senator Schumer. He wants to make this about Roe versus Wade, and about every political issue that people are interested in, but that’s not what judges do.”

Some Democrats like Sen. Bill Nelson, D-Fla., who faces a tight Senate race this November, said Monday night that they would wait to make a decision.

“I look forward to meeting with the president's nominee in the coming weeks to discuss his views on several important issues such as protecting women's rights, guaranteeing access to health care for those with pre-existing conditions and protecting the right to vote, just to name a few. I will make my decision after that,” he said.

Manchin responded to the announcement with a statement saying the judge's health care views would be a top focus: "I will evaluate Judge Kavanaugh’s record, legal qualifications, judicial philosophy and particularly, his views on health care," he said in a statement. "I’m very interested in his position on protecting West Virginians with pre-existing conditions."

A number of outside groups are already targeting vulnerable Democrats. That list includes including pro-Trump group America First Policies, which is planning to launch a seven-figure ad campaign to pressure the incumbent senators to vote in favor of the nominee. The Judicial Crisis Network also has a $1.4 million ad buy on national cable, digital and in four states represented by red state Democrats. And Americans for Prosperity, the group backed by the Koch brothers, has committed seven figures in ads and grass-roots engagement to support Kavanaugh.