Fresh off his election as speaker of the House of Representatives, US congressman Paul Ryan has refused to co-operate with President Barack Obama on immigration, ruling out any reform before 2017.
"You cannot trust this president on this issue," Ryan told CNN.
The Republican politician made the rounds of the country's Sunday morning talk shows, following a vote that swept him into the most powerful job in congress on Thursday.
Obama, whose term ends in January 2017, sidestepped gridlock in congress on immigration by signing a number of executive orders on the topic since the end of last year.
"I think it would be a ridiculous notion to try and work on an issue like this with a president we simply cannot trust on this issue," Ryan told CBS.
"He tried to go it alone, circumventing the legislative process with his executive orders."
Obama had made immigration reform a campaign promise in 2008, but he focused on other priorities early on in his administration and his recent efforts have been hampered by a Republican-dominated congress.
Some 11 million people, mostly from Mexico, are thought to live and work in the United States illegally.