US Sen. Dianne Feinstein derides 'very unusual circumstances' of Judge Neil Gorsuch's hearing.

U.S. President Donald Trump's pick to fill a Supreme Court vacancy faced intense scrutiny from Democratic senators on Monday.

Testifying during his first confirmation hearing, Judge Neil Gorsuch contended with significant opposition from Democrats who took issue with their Republican counterparts' refusal to hold a hearing for former President Barack Obama's pick to fill the post: Chief Judge Merrick Garland.

In her opening remarks, Sen. Dianne Feinstein set the stage for an intense Democratic grilling, highlighting what she called "very unusual circumstances".

"Unfortunately, due to unprecedented treatment, Judge Garland was denied a hearing and this vacancy has been in place for well over a year," she said. "I'm deeply disappointed that it's under these circumstances that we begin our hearings."

Feinstein said that in the coming days she and her Senate colleagues will seek to determine whether Gorsuch "is a reasonable mainstream conservative".

Senate Judiciary Committee Chairman Chuck Grassley, Republican, said Gorsuch was a strong defender of the Constitution's separation of powers, and would fight "executive overreach", which he said was an all-too-common practice of the Obama administration.

The ninth seat on the Supreme Court has been vacant since Associate Justice Antonin Scalia died unexpected in February 2016. The seat has gone unfilled as Republicans refused to hear any Obama nominee, hoping to hold out until last year's presidential election concluded.

"The Democrats of the Senate Judiciary Committee will extend a courtesy which Senate Republicans denied to Judge Garland; a respectful hearing and a vote," remarked Dem. Sen. Dick Durbin.

Gorsuch currently sits on the 10th Circuit Court of Appeals where he has carved out a reputation for being a strong adherent of "textualism", or a literal reading of the Constitution.

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