Republican conservatives have given John McCain a warning on what kind of justices he may appoint to the Supreme Court as president.

Their message: no surprises.

Although McCain has repeatedly vowed to nominate judges in the mold of Chief Justice John Roberts, conservatives remained skeptical of the presumptive nominee up until the eve of the GOP convention.

McCain has long had a shaky relationship with the right wing of the Republican Party because of clashes over campaign finance reform, stem-cell research, immigration and tax cuts.

Conservatives have worried that McCain might appoint another David Souter to the Supreme Court — a nominee who appeared conservative at the outset but later developed into a liberal.

Conservatives also feared that McCain might nominate a justice who took a broader view of the Constitution than more conservative jurists, who would likely strike down McCain’s signature legislative achievement: the Bipartisan Campaign Reform Act of 2002, also known as McCain-Feingold.

“There was talk of [Former Pennsylvania Gov.] Tom Ridge and talk of [Sen.] Joe Lieberman [I-Conn.] and that put conservatives in a restless state,” said Connie Mackey, vice president of the legislative action arm of the Family Research Council, in reference to two men whom McCain considered as his running mate and who both support abortion rights.

“Putting as much assurance in a document like the platform was important to conservatives,” said Mackey, who pushed for inclusion of the new language on judicial nominees in the platform.

The platform makes clear that McCain should appoint jurists who have clearly defined views of constitutional interpretation.

It states: “We oppose stealth nominations to the federal bench, and especially the Supreme Court, whose lack of a clear and distinguished record leaves doubt about their respect for the Constitution.”

Conservative activists led by Manuel Miranda, chairman of the Third Branch Conference, a coalition of conservative leaders active on judicial matters, began pushing for the platform changes in May. It began a minuet between the McCain campaign and its conservative skeptics that eventually shaped the presidential platform.

Seeking to court more support at a time when many Republicans questioned his conservative credentials, McCain included their principles in an important speech he gave at Wake Forest University later that month.

“McCain has reached out to conservatives on judges,” said Miranda. “He allowed the platform committee to function without interference from him and his campaign. That was a smart move, because it showed that he wanted to let the conservatives affect the platform.”

The activists worked with Republican National Committee staff early in the process to shape the platform, according to a conservative leader.

Conservatives also pushed for language in the platform opposing litmus tests for justices, a term that refers to the practice of asking a jurist how he or she would rule on a particular issue.

“One of the great questions about McCain stems from his signature legislation, McCain-  Feingold,” said David Keene, chairman of the American Conservative Union and a columnist for The Hill.

Keene said that some conservatives are worried about whether McCain would appoint a justice in the mold of Roberts or Justice Samuel Alito, who would be likely to strike down his signature legislative achievement.

“There was some concern that would create a lot of tension when it came [time] to appoint a justice,” said Keene. “Litmus tests, even if they are not mentioned, are sometimes real.”

The platform states that a Republican president should not appoint a judge or justice based on how he might rule on a certain issue:

“We reject the Democrats’ view that judicial nominees should guarantee particular results even before a case is filed.”

Tucker Bounds, a spokesman for the McCain campaign, reiterated that McCain would appoint jurists who take a literal view of the Constitution.

“John McCain has been clear that he will appoint strict-constructionist jurists, and judges that won’t legislate from the bench,” said Bounds.

Conservative leaders who worked on the platform said the strength of the document and McCain’s selection of Alaska Gov. Sarah Palin as a running mate eased concerns that lingered right up until the convention.

“The two combined changed everything,” said Keene, who added that McCain gave the platform committee wide latitude to draft the GOP’s core principles. “One of the points of contention with McCain was the fear born of what he said in the past, that if he had his way he would remake the party to have the conservatives on the outside looking in.”

Keene believes the 2008 platform is the most conservative since the 1976 Republican convention, when former President Gerald Ford, who nearly lost the nomination to Ronald Reagan, avoided a fight with conservatives by letting them draft the platform without interference.

Conservative activist leaders said the 2008 platform has strong stances on issues McCain and the party base have clashed over in the past.

The 2008 platform includes a complete ban on embryonic stem-cell research and also takes a harder line on illegal immigration than the 2004 platform.