Brownback, on the campaign trail in Iowa last week.
WASHINGTON (CNN) - Today's vote on the Senate immigration bill was a tough one for Kansas Sen. Sam Brownback.
The GOP presidential hopeful, who has supported the bill until now, voted yes for cloture on the measure before switching his vote fifteen minutes later to no. A vote for cloture is an indication of support for the measure.
Since the bill fell 14 votes shy of the 60 required for cloture, many in Congress have pronounced the bill dead.
Many conservatives - and likely GOP primary voters - have expressed ardent disapproval for the bill, claiming it amounts to amnesty.
Sen. John McCain, the other GOP senator running for president and a chief sponsor of the measure, voted for cloture on the bill.
UPDATE: Brownback's campaign has released a statement from the Kansas Republican on his vote against cloture.
"I voted against the Senate immigration bill because I am not convinced it would fix our broken immigration system and it would most likely repeat the mistakes of the 1986 reform."
- CNN Ticker Producer Alexander Mooney