Brownback defended his immigration vote switch Friday.
In an interview with CNN Radio Friday, the presidential hopeful claimed he was trying to send two messages at once.
"I wanted to send a clear signal that I am for comprehensive immigration reform but now is not the time, this is not the vehicle,” Brownback said.
The Kansas Republican initially voted in favor of cloture, or keeping the bill alive, during the pivotal Thursday roll call. But 15 minutes after he cast that vote, a flurry of opposition crystallized into 45 fatal votes against the bill and it became clear the bill was going to die. At that point, Brownback changed position.
The cloture vote ultimately would fail 46-53, 14 votes short of the 60 it needed to survive. Brownback is among 18 Senators who voted for cloture on one aspect of the bill Tuesday, but then voted against it Thursday.
He is the only senator known to change votes during the roll call.
When pressed, Brownback again insisted the fast change was a conscience message about immigration policy change.
"This vehicle’s not the right vehicle to do it, that’s why I did it that way," he said.
- CNN Radio's Dick Uliano and Lisa Goddard contributed to this report