The influential conservative magazine National Review called Monday for Newt Gingrich to leave the Republican primary contest.

Repeating its past criticisms of Gingrich the magazine's editorial said "it would be a grave mistake for the party to make someone with such poor judgment and persistent unpopularity its presidential nominee."

It pointed out the former House speaker, when he led in the polls, called for Rick Santorum to leave the race, "on his own arguments the proper course for him now is to endorse Santorum and exit." The magazine also highlighted that Santorum has won more contests and delegates than Gingrich and is beating him in recent polling.

The editorial said it is not clear if Gingrich "remains in the race because he still believes he could become president next year or because he wants to avenge his wounded pride; an ambiguity that suggests the problem with him as a leader."

Gingrich's campaign did not immediately respond to a request for comment on the National Review editorial.

While the magazine complimented Santorum as "conducting himself rather impressively" by showing some humility and emphasizing the declining stability of the middle class as a key issue, it said his most immediate challenge is "proving he can run a national campaign."

However, its harshest words were directed at Mitt Romney, calling him "undramatic" and a "transactional politician."

"Romney is trying to win the nomination by pulverizing his rivals ... but his attacks on Santorum have been lame, perhaps because they are patently insincere," the editorial said.

As a leading voice for conservatives, the magazine had some advice for Romney: tell the right wing of the party what it will get out of a presidency if he wins-- such as entitlement reform, more market-oriented health care, judges whose philosophy aligns with its strict interpretation of the Constitution and tax reform.

Saying so far the former Massachusetts governor has mostly been running on his business background and being a family man, "Republicans, even the many who are well disposed to him, have been saying as loud as they can: it isn't enough."