National Review, one of the most influential conservative publications in the United States, urged right-wing voters on Friday not to support Donald Trump, arguing that the New York businessman is a “philosophically unmoored political opportunist” who would trash the ideological consensus within the Republican Party “in favor of a free-floating populism with strong-man overtones.”

With only two weeks to go before Iowa kicks off what could be months-long contest for the Republican presidential nomination, the magazine’s stand against Trump — who is still leading in the polls — could be the start of a concerted effort to stop the real-estate mogul and prevent an all-but-certain defeat in November’s election against the Democrats’ Hillary Clinton.

“This is the time to mobilize,” National Review‘s editor, Rich Lowry, told Politico.

The establishment is AWOL, or even worse, so it’s up to people who really believe in these ideas and principles, for whom they’re not just talking points or positions of convenience, to set out the marker.

Establishment

Except National Review is very much part of the Republican establishment if broadly defined as a coalition of elected, local and state party officials as well as donors, insiders and affiliated interest and lobby groups. They comprise “the” Republican Party and, argued political scientists Marty Cohen, David Karol, Hans Noel and John Zaller in 2008, are the ones who really decide the presidential primary election.

They don’t make their decisions in smoke-filled rooms behind closed doors. Rather, such professional Republicans influence the nominating process in myriad subtle ways, from writing caucus and primary rules to appointing superdelegates and paying for commercials.

National Review‘s anti-Trump barrage is unusual in its breadth. The magazine has collected contributions from opinion leaders as diverse as the rabble-rousing Glenn Beck and William Kristol, the hawkish editor of The Weekly Standard, to the libertarian Cato Institute’s David Boaz and the president of the pro-business Club for Growth, David McIntosh (underlining that Trump has no actual constituency in the conservative movement).

But it is not unusual for movement and party leaders to signal their preferences to voters and nudge them toward supporting a candidate who will actually advance their agenda. Which is, after all, what a political party is for.

As we have reported, the biggest Republican donors are still on the fence and many elected officials have yet to take sides. Both are probably waiting for the early voting contests in Iowa, New Hampshire and South Carolina to provide fresh evidence about who is electable and can stop both Trump and Clinton.

Conservatives activists, however — the ones who are paying the closest attention — are making up their minds. They may not yet agree on who should be the nominee, but National Review‘s campaign makes clear they agree it must not be Trump.