Senator Kerry said he hoped the delay would be short
Monday's unveiling of a climate bill in the US Senate has been postponed, after a row over immigration reforms.
The announcement was made by Democratic Senator John Kerry, one of the authors of the bi-partisan bill.
It came after Republican Senator Lindsey Graham, a co-author, threatened to withhold support if the Democrats pushed ahead with an immigration bill.
The climate bill reportedly aims to cut greenhouse gases to 17% below 2005 levels by 2020.
"Regrettably, external issues have arisen that force us to postpone only temporarily," Senator Kerry said in a statement.
But he said he was confident the delay would be short.
"We all believe that this year is our best and perhaps last chance for Congress to pass a comprehensive approach," he added.
His comments came after Senator Graham had said he would have to drop out of drafting the bill because of concerns that Democrats wanted to focus on an immigration bill first.
"Moving forward on immigration - in this hurried, panicked manner - is nothing more than a cynical political ploy," Senator Graham said.
He was reportedly unhappy that Democrats were considering a bill to grant legal status to long-term illegal immigrants - just months before November's congressional elections.
Many of the migrants staying in the US are Hispanics, who traditionally back Democrats.