"The president has chosen someone with suitable legal credentials, but that is not the end of our inquiry. The Senate must review Judge Roberts' record to determine if he has a demonstrated commitment to the core American values of freedom, equality and fairness." - Senate minority leader Harry Reid, D-Nev.
"Judge Roberts is the kind of outstanding nominee that will make America proud. He embodies the qualities America expects in a justice on its highest court: someone who is fair, intelligent, impartial and committed to faithfully interpreting the Constitution and the law." - Senate Majority Leader Bill Frist, R-Tenn.
"We are extremely disappointed that President Bush has chosen such a divisive nominee for the highest court in the nation, rather than a consensus nominee who would protect individual liberty and uphold Roe v. Wade." - NARAL Pro-Choice America.
Roberts "rules based on the application of existing laws and specific facts of the cases before him, rather than making new laws or creating new policies based on personal opinion." - Sean Rushton, director of the conservative Committee for Justice.
"I look forward to the Committee's findings so that I can make an informed decision about whether Judge Roberts is truly a guardian of the rule of law who puts fairness and justice before ideology." - Sen. Hillary Rodham Clinton, D-N.Y.
"Senate Democrats, especially those seeking re-election next year, should know that we will be watching them carefully. If they again attempt to attack a nominee's faith or pro-life convictions, their constituents will know about it and they will be held accountable." - Father Frank Pavone, national director, Priests for Life.
"John Roberts' record raises serious concerns as well as questions about where he stands on crucial legal and constitutional issues. Replacing O'Connor with someone who is not committed to upholding Americans' rights, liberties and legal protections would be a constitutional catastrophe." - Ralph Neas, president of the liberal People for the American Way.
"He's the kind of judge that all of us want - someone committed to applying the law impartially rather than legislating from the bench." - Sen. Orrin Hatch, R-Utah.
"The burden is on a nominee to the Supreme Court to prove that he is worthy, not on the Senate to prove he is unworthy." - Sen. Charles Schumer, D-N.Y.
"Liberal pressure groups will insist that Senate Democrats filibuster against Judge Roberts, unless he pledges in advance to vote against allowing elected legislators to place meaningful limits on abortion." - Douglas Johnson, legislative director of the National Right to Life Committee.
"Without prejudging the nominee, I do believe Judge Roberts' record raises questions about his commitment to the right to privacy, protection of the environment and other important issues." - Sen. Barbara Boxer, D-Calif.
"I'm hopeful that in the coming weeks we can avoid vicious character assassinations and attacks in this confirmation process." - Sen. George Allen, R-Va.
"The president had an opportunity to unite the country with his Supreme Court nomination, to nominate an individual in the image of Justice Sandra Day O'Connor. Instead, by putting forward John Roberts' name, President Bush has chosen a more controversial nominee and guaranteed a more controversial confirmation process." - Sen. Dick Durbin, D-Ill.
"I can't help but think that he will continue to impress as a person of fairness, thoughtfulness and just the kind of judge who will bring a nonpolitical approach to judging. ... I think he's going to be well received." - Sen. Jeff Sessions, R-Ala.
"This is a very, very activist court. I want to know whether he's going to be like that, somebody who would eagerly and willingly overturn settled law." - Sen. Patrick Leahy, D-Vt.
"This is a task so important that partisan politics must be set aside." - Sen. Kay Bailey Hutchison, R-Texas.
"I urge the Senate to move swiftly to hold hearings and give Judge Roberts an up or down vote. Quick action will ensure that both branches - the Congress and the Supreme Court - can return to their normal process without long, distracting partisan disruption." - House Speaker Dennis Hastert, R-Ill.
"There were a lot of unknowns about Justice Souter. He really was almost a blank slate. It's not the same with Judge Roberts. He has clearly enunciated his view of his judicial philosophy." - Tony Perkins of the conservative Family Research Council.