Sonia Sotomayor, President Obama's nominee to replace Justice David Souter on the U.S. Supreme Court, is posing a conundrum for Republicans who are struggling to unite against a woman they presume will be a reliable vote for liberal causes.

The GOP doesn't want to give Sotomayer a free ride, because they believe she is a judicial activist who will legislate from the bench.

But they're also concerned that if they launch a no-holds barred attack on Sotomayor, the first Hispanic to be nominated to the court, they risk alienating a growing minority they want on their side in the voting booth.

The White House warned earlier this week that detractors should be careful as they scrutinize Sotomayor's  record and background.

"It is probably important for anybody involved in this debate to be exceedingly careful with the way in which they've decided to describe different aspects of this impending confirmation," White House spokesman Robert Gibbs said.

Elected Republican officials have heeded that warning so far, holding fire as they continue to dig into the judge's past.

But two unelected Republican stalwarts, Rush Limbaugh and former House Speaker Newt Gingrich, haven't been as restrained. They have labeled Sotomayor a "reverse racist" for saying in a speech in 2001 that she hopes a "wise Latina woman with the richness of her experiences would more often than not reach a better conclusion than a white male who hasn't lived that life."

Their comments have drawn pushback from Republican elected officials and other commentators.

"I think it's terrible. This is not the kind of tone that any of us want to set when it comes to performing our constitutional responsibilities of advice and consent," Sen. John Cornyn, R-Texas, told National Public Radio on  Thursday.

"Neither one of these men are elected Republican officials," Cornyn said. "I just don't think it's appropriate and I certainly don't endorse it. I think it's wrong."

Sen. Orrin Hatch, R-Utah, told CNN that he disagrees with Gingrich.

"Frankly, I think it is a little premature and early, because she hasn't had a chance to explain some of these comments that she has made," Hatch said. 

"I think we have to be fair. I think we have to do what is normally done, and that is scrutinize the record, look at the opinions, the unwritten opinions, the articles, the speeches, the various comments that have been made and so forth, and do it fairly."

In her Wall Street Journal column on Friday, conservative commentator Peggy Noonan panned Gingrich for twittering that Sotomayor should withdraw because a white judicial nominee would have to if he made a similar statement on race.

"Does anyone believe that?" Noonan wrote. "[Gingrich] should rest his dancing thumbs, stop trying to position himself as the choice and voice of the base in 2012, and think."

She urged Republicans to act like grownups as they challenge Sotomayor's nomination, which she called a "brilliant political pick" because the GOP has struggled to attract and retain Hispanics and women, and because Sotomayor's rags-to-riches story is so moving.

"Politically she's like a beautiful doll containing a canister of poison gas: Break her and you die," Noonan wrote.

Noonan questioned the wisdom of critics who want to use an attack on Sotomayor as a way to excite the base.

"Excite the base? How about excite a moderate, or interest an independent?" she wrote. "How about gain the attention of people who aren't already on your side?"