The issue focused on four Republican senators: Kelly Ayotte of New Hampshire, Jeff Flake of Arizona, Bob Corker of Tennessee and Pat Toomey of Pennsylvania.

In the past, Mr. Cruz has taken to Twitter to pressure Mr. Ayotte to change her position. The Cruz campaign had already asked her to leave the stage on Tuesday if she did not support Mr. Trump.

If she changes her mind, "if she actually goes with the people of New Hampshire and they tell her that they