The supreme court nomination of Ketanji Brown Jackson should be placed “beyond politics”, the politician who extracted Joe Biden’s politically priceless promise to instal the first Black woman on the court said on Sunday.

Biden introduced Jackson as his pick to replace the retiring Stephen Breyer this week.

Some Republicans have complained that nominations should not be made on grounds of race or gender – ignoring promises to put women on the court acted on by Ronald Reagan and Donald Trump.

Others have complained about how Democrats treated one of Trump’s nominees, Brett Kavanaugh, who denied allegations of sexual assault. Others have objected on ideological grounds, for example Lindsey Graham, a member of the Senate judiciary committee, claiming the Jackson nomination was the work of the “radical left”.

James Clyburn, the South Carolina congressman and House Democratic whip whose endorsement both propelled Biden to the presidential nomination and produced his promise to pick a Black woman, appeared on Sunday on CBS’s Face the Nation.

He said: “This is beyond politics. This is about the country, our pursuit of a more perfect union, and this is demonstrative of another step in that pursuit.”

Of 115 supreme court justices, 108 have been white men. Two have been Black men, five women. As well as being the first Black woman on the court, Jackson would be the fourth woman on the current nine-justice panel, joining liberals Elena Kagan and Sonia Sotomayor and Amy Coney Barrett, a hardline conservative.

Clyburn said he hoped “that all my Republican friends will look upon” the nomination of Jackson as being “beyond politics”.

“Let’s have a debate,” he said. “Let’s talk to her about her rulings and about her philosophy. But in the final analysis, let’s have a strong bipartisan support to demonstrate that both parties are still in pursuit of perfection”.

No supreme court nomination – or, most observers would argue, hearing or ruling – is ever above politics. If confirmed, Jackson will not alter the balance of a court tilted 6-3 to conservatives by Republican political hardball which gave Trump three picks.

Before Biden made his decision, Clyburn and Republicans including Graham and the other South Carolina senator, Tim Scott, championed J Michelle Childs, a judge from their state. Clyburn said it would be important to instal a justice who did not go to Yale or Harvard. Jackson went to Harvard.

“It’s more traditional, no question about that,” Clyburn told CBS. “This means that we will continue that tradition, and I am one, as you can see, that’s not so much for tradition. I want to see us break as much new ground as possible.

“But … in the final analysis, I think this is a good choice. It was a choice that brings on to the court a background and some experiences that nobody else on the court will have. And I think when you look at not just [Jackson’s] background in the family, life, but also her profession, she was a public defender. That adds a new perspective to the court.”

Steve Vladeck, a professor at the University of Texas, has pointed out that Jackson has more trial experience than four current justices combined – including the chief, John Roberts.

Clyburn also said a successful confirmation process could help Biden politically with Black voters facing difficulties familiar to most Americans, particularly inflation.

“When you have an opportunity to make an appointment like you just had,” he said, “and he made an African American appointment, I guarantee you, you see some of that move up. It may not move up with the people who are having income problems, but it will move up to those who have other reservations about the president.”

Last year, Jackson was confirmed to the court of appeals for the DC circuit with support from three Republican senators: Graham, Susan Collins of Maine and Lisa Murkowski from Alaska.

This year, Democrats will be able to confirm Jackson simply by keeping their 50 votes together and using Kamala Harris’s casting vote as vice-president.

But on Sunday Mitt Romney of Utah told CNN’s State of the Union he could vote to confirm Jackson.

“Yes,” the former presidential nominee said, “I’m going to take a very deep dive and had the occasion to speak with her about some of the concerns when she was before the Senate to go on to the circuit court.

“Look, her nomination and her confirmation would or will be historic. And like anyone nominated by the president of the United States, she deserves a very careful look, a very deep dive. And I will provide fresh eyes to that evaluation, and hope that I will be able to support her in the final analysis.”