Neil Gorsuch, President Donald Trump's U.S. Supreme Court pick, said on Tuesday that he would have 'walked out the door' if the chief executive has asked him to over-turn Roe v Wade.

The federal judge mounted a defense of his independence as a judge as he was questioned by senators, and also suggested that the 44-year-old decision that legalized abortion, is a powerful legal precedent that would be difficult to overturn.

Gorsuch said in his confirmation hearing that the landmark women's rights case has been reaffirmed many times.

'It is a precedent of the United States Supreme Court,' Gorsuch told the Senate Judiciary Committee, 'so a good judge will consider it as precedent of the United States Supreme Court worthy as treatment of precedent like any other.'

Trump said during his presidential campaign that he would appoint only anti-abortion judges to the high court, and predicted that the long-term result would be Roe's demise.

But Gorsuch insisted the case's status as a repeatedly defended decision 'adds to the determinacy of the law. What was once a hotly contested issue is no longer a hotly contested issue. We move forward.'

Neil M. Gorsuch testified before the Senate Judiciary Committee on his nomination to be an associate justice of the US Supreme Court on Tuesday, suggesting that the 'Roe v. Wade' abortion case is a powerful precedent that would be hard to overturn

President Donald Trump, shown Monday night in Louisville, Kentucky, said during his White House campaign that he would only appoint pro-life justices to the high court

He was asked by South Carolina Republican senator Lindsey Graham how he would have reacted to a demand from Trump when the president was interviewing him to overturn Roe v Wade.

'I would have walked out the door,' he replied.

'It is not a judge's due. They should not do it a that end of Pennsylvania Avenue and they should not do it at this end, respectfully.'

The federal appeals court judge said earlier on Tuesday that he would have no trouble ruling against the president as he tried to stake out his independence amid concerns by Democrats that he would be beholden to the man who nominated him.

With the ideological balance of the Supreme Court at stake, the Senate Judiciary Committee opened the second day of its confirmation hearing for Gorsuch, a conservative federal appeals court judge from Colorado.

Republicans, who control Congress, have praised Gorsuch, 49, as highly qualified for a lifetime appointment as a justice.

Chuck Grassley, the panel's Republican chairman, asked Gorsuch 'whether you'd have any trouble ruling against a president who appointed you.'

'That's a softball, Mr. Chairman,' Gorsuch said. 'I have no difficulty ruling against or for any party, other than based on what the law and facts in the particular case require. And I'm heartened by the support I have received from people who recognize that there's no such thing as a Republican judge or a Democratic judge. We just have judges in this country.'

Gorsuch insisted he would be an independent, impartial judge who would have no problem ruling against the president who appointed him

Gorsuch cited more than a dozen cases from memory where he as ruled against corporate and government defendants and in favor of 'the little guy'

Despite slim chances of blocking his nomination in the Republican-led Senate, Democrats have raised questions about Gorsuch's suitability for the job.

'I have offered no promises on how I'd rule in any case to anyone. And I don't think it's appropriate for a judge to do so, no matter who's doing the asking. And I don't, because everybody wants a fair judge to come to their case with an open mind and to decide it on the facts and the law,' Gorsuch told the committee.

He made news quickly, declaring under questioning from ranking committee Democrat Dianne Feinstein that 'District of Columbia v. Heller,' a Supreme Court case that strengthened Second Amendment gun rights, is 'the law of the land.'

When Feinstein grilled him about a handful of decisions he handed down in favor of corporations, Gorsuch rattled off a list of more than a dozen cases where he ruled in favor of ordinary Americans and against corporate interests.

'How do we have confidence in you that you won't just be for the big corporations, that you will be for the little man?' Feinstein asked him.

'I've participated in 2,700 opinions over ten and a half years. And if you want cases where I've ruled for the little guy as well as the big guy, there are plenty of them.'

Asked to submit examples in writing, Gorsuch responded: 'I'll name a bunch of them right now!'

Among the cases he cited were decisions that protected average Americans from uranium pollution and pregnancy discrimination.

Gorsuch was accompanied to Monday's and Tuesday's hearings by his wife Louise

The Senate Judiciary Committee's ranking Democratic member Dianne Feinstein offered the first meaningful grilling of Gorsuch

Gorsuch, wearing a navy blue suit and a purple tie, shook hands with supporters and senators as he arrived in the committee room. Grassley said the hearing could last about 10 hours, with all the committee members getting to question him.

Before the hearing resumed on Tuesday, about 60 Gorsuch supporters rallied on the sidewalk outside the Senate office building, many from a student anti-abortion movement carrying signs saying, 'We don't need Planned Parenthood,' referring to the women's healthcare provider that performs abortions.

In his opening statement to the panel on Monday, Gorsuch defended his judicial record, emphasizing the need for 'neutral and independent judges to apply the law.'

Democrats outlined their lines of attack in their opening statements on Monday, with some senators saying they would press him on whether he is independent enough from Trump, who has condemned federal judges who have put on hold his two executive orders to ban the entry into the United States of people from several Muslim-majority countries.

Gorsuch will also face questioning over cases he has handled on the appeals court in which corporate interests won out over individual workers.

Committee chairman Chuck Grassley (center) offered jovial praise for Gorsuch nd no criticism

Gorsuch offered a child a fist bump before Tuesday's proceedings began

Feinstein said on Monday she wanted assurances that Gorsuch would not seek to overturn the Supreme Court's landmark 1973 case Roe v. Wade, which legalized abortion in the United States.

She and other Democrats are also expected to question Gorsuch on whether he would support gun restrictions, campaign finance laws and environmental regulations.

Grassley said on Monday the committee is likely to vote on the nomination on April 3, with the full Senate vote likely soon after. The hearing could last four days.

If Gorsuch is confirmed by the Senate, as expected, he would restore a narrow 5-4 conservative court majority. The seat has been vacant for 13 months, since the death of conservative justice Antonin Scalia.

The court's ideological leaning could help determine the outcome of cases involving the death penalty, abortion, gun control, environmental regulations, transgender rights, voting rights, immigration, religious liberty, presidential powers and more.

Republicans hold 52 of the Senate's 100 seats. Under present rules, Gorsuch would need 60 votes to secure confirmation. If Gorsuch cannot muster 60, Republicans could change the rules to allow confirmation by a simple majority.