Barring the unexpected, the Senate is likely to confirm Judge John Roberts for the Supreme Court seat of retiring Justice Sandra Day O’Connor. He could easily get the votes of virtually every one of the 55 Republicans.

But many of the 44 Democrats could face a difficult decision on Judge Roberts. His answers at this week’s Judiciary Committee hearings may go a long way toward determining how they vote.

The reason is that his extensive past writings provide ample evidence that he holds the kind of conservative views that President Bush and most fellow Republicans hope – and most Democrats fear – he’ll bring to the high court.

At the same time, every sign is that Judge Roberts is well-qualified in terms of intellect and experience, leaving his specific views as the principal reason to mount what would likely be a losing battle against his confirmation.

Unless the public sees those views as extreme, opposing Judge Roberts could pose political perils, especially for senators with national ambitions.

Already, the pressures on Democrats from their core constituencies are evident.

Liberal organizations have urged his rejection on grounds his record suggests he would threaten existing court positions on abortion, privacy and other issues.

“Confirming John Roberts would endanger much of the progress made by the nation in civil rights over the past half-century,” People for the American Way said. If he is approved, the liberal group added, “The balance of the court will shift to the right for decades to come, imperiling Americans’ constitutional rights and liberties.”

But as Judge Roberts himself said in a 2000 interview on the Belo Capital Bureau’s “Capital Conversation,” presidents have often been surprised by the way their appointees to the high court have voted.

And Justice John Paul Stevens, one of the court’s more liberal members, said in a recent speech that he has sometimes voted differently from his personal views if he felt that the law required it.

Citing his role in two recent rulings, Justice Stevens said, “In each, I was convinced that the law compelled a result that I would have opposed if I were a legislator.”

So far, Democrats have mostly held their fire. Though some of the more liberal senators have criticized various Roberts comments, none has committed to vote against the nomination.

Two of the more conservative Democrats, Sens. Ben Nelson of Nebraska and Mary Landrieu of Louisiana, said they are leaning toward voting for him.

A lot may depend on how senators react to his testimony. Judge Roberts will undoubtedly be pressed for his views on privacy as a way to get at his views on abortion. But he will certainly seek to avoid specifics suggesting a particular position in a particular case.

That could leave the Democrats with the dilemma of whether to give the benefit of the doubt to a judge they believe would not be on their side of divisive issues.

In recent statements, California’s two Democratic senators indicated how noncommittal answers by Judge Roberts could produce two opposite reactions.

Sen. Barbara Boxer, the more liberal of the two, said she would vote against him unless he backs rights she considers essential, including abortion and privacy.

“I need to know exactly where he will stand,” she told reporters in San Francisco.

That may be a tough test for the judge to meet.

Sen. Dianne Feinstein took a different approach.

Declaring she felt ” a special obligation” as the only woman on the Judiciary Committee, she told a business group in San Jose that “it would be very difficult for me to vote ‘yes’ on a nominee I thought would overturn Roe v. Wade.”

But it’s unlikely that Judge Roberts will be specific enough in his responses so that she would know for sure how he would rule.

In the end, political considerations may influence how many Democrats cast a vote that pleases their hard-core supporters and how many take a view that might be seen as less reflexively partisan.

After all, Bush picked a nominee he thought would gain strong support in the Senate. And Democratic senators such as Hillary Clinton and Joseph Biden might be thinking of a day when they will want some GOP backing for liberal judicial nominees.

Carl P. Leubsdorf is Washington bureau chief of the Dallas Morning News.