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Supreme Court nominee John Roberts (search) was up on Capitol Hill for a second day Wednesday with Democratic Sen. Bill Nelson of Florida after a rare August recess courtesy call with Oregon Democratic Sen. Ron Wyden on Tuesday.

The two practically had the Capitol to themselves.

"Nobody's around and the two of us are trying to convince you we're working," Wyden said.

"I am trying to get ready for the hearings," said Roberts.

While Congress is out, several groups have been weighing Roberts' nomination.

One conservative group, Virginia-based Public Advocate of the United States, said it will oppose Roberts because he once spent six hours helping a gay rights group prepare its case for a Supreme Court hearing opposing a 1992 Colorado ballot initiative that would have barred laws, ordinances or regulations protecting gays from discrimination in housing, work and at public agencies.

On the flip side, NARAL Pro-Choice America has launched a new television ad accusing Roberts of supporting violent abortion protesters. The abortion rights advocates are criticizing a brief Roberts signed while in the solicitor general's office of President George H.W. Bush in which the administration argued that a 19th century anti-discrimination act aimed at the Ku Klux Klan could not be used by abortion clinics to stop protesters outside their facilities.

"John Roberts filed court briefs supporting violent fringe groups and a convicted clinic bomber," says the ad, which then accuses Roberts of "excusing violence" at these clinics. A White House spokesman dismissed the ad as "outrageously false." Despite its wording, NARAL officials say the ad is not intended to suggest that Roberts condones clinic violence.

The ad comes at a time in which the Bush administration is urging the nation's highest court to uphold a New Hampshire law requiring parental notification for minors who want abortions.

The case, which will be heard this November when Roberts could potentially be on the court, is important not only because it raises the issue of whether a parental notification requirement must contain an exception for the health of the mother, but also because it revisits the question of how tough the standard should be when a court evaluates restrictions on abortion — issues on which the high court has been divided in the past.

Through the Justice Department, President Bush filed an amicus, or "friend of the court" brief on Monday advocating an arguably easier threshold of proof for those defending abortion restrictions, and saying the New Hampshire law is above board even though it doesn't contain a health exception. The administration pointed out that a judge can always override the parental notification requirement when to do so would be in the best interests of the minor.

Meanwhile, Sen. Arlen Specter (search), R-Pa., chairman of the Senate Judiciary Committee, sent a letter to Roberts on Monday alerting the nominee of the growing concern over Supreme Court criticism of Congress, specifically its overturning of laws where Congress used its powers to regulate interstate commerce, combat violence against women and prevent firearms near school grounds. Specter labeled these decisions "judicial activism."

"I do see a great deal of popular and congressional dissatisfaction with the judicial activism; and, at minimum, the Senate's determination to confirm new justices who will respect Congress' constitutional role," Specter wrote in his letter to Roberts.

Democratic New York Sen. Charles Schumer said Specter has now paved the way for liberal Democrats to grill Roberts on abortion, civil rights and environmental regulations. Legal analysts were more cautious.

"Arlen Specter's concerned about the Supreme Court criticizing Congress. It means Arlen Specter is a member of Congress, not a member of the Democratic Party. You know, you would think that politicians have a little thicker skin than that," said former Justice Department official Victoria Toensing.

On the issue of congressional intervention, Wyden told The New York Times in Wednesday's edition that he asked Roberts about Congress' role in trying to influence the outcome of cases, and pointed to the intervention by Congress into the life of brain-damaged woman Terri Schiavo.

Wyden said his staff wrote down Roberts' response word for word, which while not addressing Schiavo specifically, indicates how much Roberts values judicial independence.

"His answer was, 'I am concerned with judicial independence. Congress can prescribe standards, but when Congress starts to act like a court and prescribe particular remedies in particular cases, Congress has overstepped its bounds,'" Wyden said quoting Roberts.

The White House, however, later complained that Wyden's transcription clearly omitted the words, "I am aware of court precedents which say," that apparently preceded his comments on Congress prescribing standards.

The passage indicates Roberts was referring to precedent, not to his own views or concerns as the Times article suggests, the White House argued. That is why officials there have asked the paper for a correction.

A source in the meeting also said Roberts specifically asked not to discuss Schiavo, saying, "I haven't studied the Schiavo case and I wouldn't want to opine on it."

In Chicago, Supreme Court Justice Stephen Breyer (search) joked Tuesday about how confirmation battles look to Supreme Court nominees.

"It's like asking for the recipe for chicken á la king from the chicken," he said.

At the same American Bar Association conference panel, South Carolina Republican Sen. Lindsey Graham said the Senate will be tested as much as Roberts.

"I predict the confirmation process will be appropriately heated, appropriately confrontational but in the end, the word 'appropriate' will have survived. And I think the Senate is going to take the opportunity to start over again," he said.

Late Tuesday, Vermont Sen. Patrick Leahy, the ranking Democrat on the Judiciary Committee, lodged another complaint about access to some of Roberts' files while a Justice Department attorney.

In a letter to the White House, Leahy said the White House appears to have released some of the files to reporters before giving them to committee Democrats, a process Leahy said undermines their ability to prepare for hearings that begin on Sept. 6.

On that day, Roberts will likely be introduced by Republican Virginia Sen. John Warner and perhaps Indiana Sens. Evan Bayh and Richard Lugar. Roberts was born and raised in Indiana. The nominee will also make an opening statement before being addressed by committee members. Questions are likely to last for more than one day.

Click in the box near the top of the story to watch a report by FOX News' Major Garrett.

FOX News' Megyn Kendall and Brian Wilson contributed to this report.