Immigration could set stage for big U.S. budget showdown

Conservatives in the U.S. Congress who object to President Barack Obama's immigration policies are threatening to tie a must-pass budget bill to the issue, making for a possible showdown in September and raising the specter of a government shutdown.

White House-Congress tensions rose on Wednesday when Obama spokesman Josh Earnest said the president's upcoming decision on steps to possibly ease some immigration rules would not be affected by Republican tactics.

If the president wields his pen and commits that unconstitutional act to legalize millions, I think that becomes something that is nearly political nuclear," the Des Moines Register newspaper in Iowa quoted Republican Representative Steve King saying at a meeting of conservative Republicans.

Obama has said he will use his executive powers at the end of summer because Republicans have blocked changes to an antiquated, unworkable U.S. immigration law.