The Club for Growth, which has long opposed GOP frontrunner Donald Trump and recently endorsed Sen. Ted Cruz (R-TX), is planning to run an anti-Trump television ad in Wisconsin ahead of the state’s primary on April 5.

“Donald Trump is the worst candidate in the Republican field, and he can’t win in November,” said Club for Growth president David McIntosh. “It’s time for Republicans to rally around Ted Cruz, the one candidate who can lead the party to victory.”

The 30- second ad titled “Math” states:

IF YOU DON’T WANT DONALD TRUMP TO WIN, YOUR CHOICE COMES DOWN TO THIS: MATH.

ONLY TED CRUZ CAN BEAT DONALD TRUMP.

JOHN KASICH CAN’T DO IT.

THE MATH WON’T WORK.

A VOTE FOR KASICH ACTUALLY HELPS TRUMP, BY DIVIDING THE OPPOSITION.

IT’S TIME TO PUT DIFFERENCES ASIDE.

TO STOP TRUMP, VOTE FOR CRUZ.

The $1 million ad buy will begin airing on March 26.