The Nevada Democrat said Democrats want more time to read the bill.
The Florida Republican said Democrats face a "stark choice" on the Iran deal.
Senators are still working out details of the measure hours before the first procedural vote.
Reid pressured Republican candidates to "name one difference" they have with Trump on immigration.
Keith Laing 07/21/15 09:11 AM EDT
The drive for a new highway bill is scheduled to begin with a procedural vote Tuesday.
But Republicans could face a tough battle.
"What happened in Chattanooga can never happen again," Rep. Jerry Moran said.
Sen. Bob Corker (R-Tenn.) said "bipartisan skepticism" surrounds the deal.
Sen. Claire McCaskill says Cruz is "following Trump around like a lost puppy."
The 2016 hopeful slammed Obama's moves on Iran and Cuba, calling it "capitulation Monday."