WASHINGTON - Sonia Sotomayor told her up-from-the-bootstraps story yesterday to the Senate Judiciary Committee and declared that a judge's role is "not to make law; it is to apply the law." But skeptical Republicans warned that they would ask tough questions beginning today about her background and activism.

The 55-year-old federal appeals judge sought to reassure the committee that she would be impartial.

"In the past month, many senators have asked me about my judicial philosophy," the first Hispanic Supreme Court nominee said. "It's simple: fidelity to the law."

Sotomayor's testimony capped a day in which Democrats hailed the historic nature of her nomination and Republicans raised questions about whether she displayed too much empathy in her rulings.

By the end of the day - a largely polite five hours of opening statements by the nominee and the committee's 12 Democrats and seven Republicans - there were no obvious roadblocks to her confirmation to succeed retired Justice David H. Souter.

"Unless you have a complete meltdown, you're going to get confirmed," said Sen. Lindsey Graham (R., S.C.), even though he and his Republican colleagues offered a long list of concerns.

The committee's senators will begin questioning Sotomayor today; each will get about 30 minutes. Yesterday, the Republicans made their line of questioning clear.

"President Obama said that he would nominate judges based on their ability to empathize in general and with certain groups in particular. This empathy standard is troubling to me," said Sen. Charles Grassley (R., Iowa). "The Constitution requires that judges be free from personal politics, feelings, and preferences."

Sotomayor signaled that she was ready for their queries. She opened her testimony by acknowledging her mother, Celina, and her brother, Juan, turning around to whisper, "Mom, thank you," and then recalling her days growing up in the South Bronx.

"The progression of my life has been uniquely American," she said. "My parents left Puerto Rico during World War II. I grew up in modest circumstances in a Bronx housing project. My father, a factory worker with a third-grade education, passed away when I was 9 years old."

Her mother, she said, taught her that "the key to success in America is a good education." As a lawyer, she has seen the judicial system from several perspectives: as a prosecutor in New York, a corporate attorney, a trial judge, and a judge on the New York-based Second Circuit appeals court.

Further, she said in a retort to Republican criticism that she gets too personal in her rulings, "my career as an advocate ended - and my career as a judge began - when I was appointed by President George H.W. Bush" to her first court post in 1992.

The hearing began quietly yesterday as Judiciary chairman Patrick J. Leahy (D., Vt.) recalled other historic "firsts" on the court and how they were challenged because they didn't fit familiar molds.

Today, he said, "we're in a different era," and added that he hoped Sotomayor would get the same kind of consideration as Sandra Day O'Connor, whom President Ronald Reagan named as the first woman on the Supreme Court in 1981. O'Connor won overwhelmingly bipartisan support.

Obama "has done his part" in nominating Sotomayor, Leahy said. "He's made an historic nomination." Her record is so extensive, added Sen. Charles Schumer (D., N.Y.), who introduced her to the committee, that "I believe these hearings will matter less" than usual.

As Sen. Dianne Feinstein (D., Calif.) also was praising the nominee, a man leapt up in the audience and hollered, "What about the unborn? Abortion is murder!" Police quickly removed him from the room.

Sen. Jeff Sessions of Alabama, the committee's top Republican, offered the GOP philosophy, expressing concern that too often "a judge is free to push his or her own courtroom political and social agenda."

"I reject this view," he said.

Too often, he contended, Sotomayor has a philosophy that "allows subjectivity" and affects her rulings on issues such as abortion, gun control, private-property rights, and capital punishment.

Sessions and other Republicans vowed to scrutinize her controversial rulings and Hispanic-rights activism.

From 1980 to 1992, Sotomayor was active with the Puerto Rican Legal Defense and Education Fund, whose priorities ranged from boosting bilingual education to opposing the death penalty. Republican critics cite these Puerto Rican advocacy efforts as a signal that Sotomayor is outside the mainstream.

Graham also singled out as particularly troubling the nominee's widely reported 2001 comment that a "wise Latina" could come to better conclusions than a white male.

"If I had said anything remotely like that, my career would have been over," Graham said. "I think your experience can add a lot to the court, but I don't think it makes you better than anyone else."

Sotomayor also sided in a recent discrimination case with the city of New Haven, Conn., which denied promotions to several white firefighters because no blacks and only one Hispanic had scored high enough on the promotion exam. The Supreme Court overturned that decision last month.

Two of those firefighters are expected to testify this week. Last week, McClatchy Newspapers reported that the left-leaning group People for the American Way was quietly targeting one of them by encouraging the news media to scrutinize "the troubled and litigious work history" of firefighter Frank Ricci, the lead plaintiff in the case.

Republicans are aware, however, that they need to be careful not to alienate Hispanics by appearing to attack Sotomayor unfairly.

"My Republican colleagues who vote against you, I assure you, could vote for a Hispanic nominee," Graham told Sotomayor, adding that he had not decided how he would vote. "They just feel unnerved by your speeches and by some of the things that you've said and some of your cases."

Sotomayor indicated she was ready to address those concerns.

In the days ahead, she said, she hoped it would become clear "that my record in two courts reflects my rigorous commitment to interpreting the Constitution according to its terms; interpreting statutes according to their terms and Congress' intent; and hewing faithfully to precedents established by the Supreme Court and by my circuit court."

"In each case I have heard," she said, "I have applied the law to the facts at hand."

Today's Schedule

The Senate Judiciary Committee reconvenes its confirmation hearing for Sonia Sotomayor at 9:30 a.m. today.

The nominee will face a first round of questions from each of the 19 Judiciary members - 12 Democrats and seven Republicans. The questioning is expected to extend into tomorrow.