(CNSNews.com) - Conservatives stand a strong chance of securing at least one more seat on the U.S. Supreme Court before President Bush leaves office, according to one conservative court-watcher.

Ed Whelan, president of the Ethics and Public Policy Center, didn't say who might be the next justice to leave, but speculation has recently swirled around Associate Justice John Paul Stevens, a Gerald Ford appointee, who will turn 87 in April.

Whelan told a gathering of conservatives on Saturday that it is important to nominate a compelling presidential candidate in the 2008 presidential campaign because the next president may have the opportunity to appoint up to six new Supreme Court justices.

In addition to Stevens, Associate Justices Ruth Bader Ginsburg, Antonin Scalia and David Souter are among the most likely to step down between now and 2016, Whelan said.

When Justice Sandra Day O'Conner sat on the Supreme Court, she was among six justices who embraced the type of judicial activism that Whelan rejects.

He mentioned that some justices think they have the unbounded authority to tell "you yahoos" what to do. "No justice who holds this view should sit on the court," he added.

With O'Connor now retired, Whelan said his motto is "one down and five to go." (The other five apparently include Souter, Ginsburg, Stevens, Anthony Kennedy and Stephen Breyer.)

Although some conservatives might view the new Democratic majority in the U.S. Senate as an insurmountable obstacle to the confirmation of a quality justice, Whelan does not believe this to be the case.

He acknowledged a certain "timidity" on the part of some Senate Republicans and some White House officials who wish to avoid a confirmation battle. Nevertheless, Whelan said there is good reason to take heart from the last two confirmation hearings involving John Roberts and Samuel Alito.

Those lessons are that quality counts; and that the notion of judicial restraint is held in high public esteem, he argued.

"Wide swaths of the American public consider themselves conservative," Whelan said. "And they understand and appreciate appeal of the image of judge as umpire."

Moreover, Democrats are often reluctant and quite "timid" themselves in openly defending judicial activism, he added.

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