President Donald Trump gave Democrats two weeks to work on immigration reform and stem the flow of migrants at the southern border, but cast doubt on getting action from Congress and vowed to go ahead with a roundup of people facing deportation.

"I want to give the Democrats every last chance to quickly negotiate simple changes to Asylum and Loopholes," Trump said in a tweet on Sunday, referring to laws he's seeking to change. "Probably won't happen, but worth a try. Two weeks and big Deportation begins!"

House Speaker Nancy Pelosi spoke by telephone with Trump Friday night, asking him to call off the raids, according to a person familiar with the discussion. Pelosi said the delay was welcome. "Time is needed for comprehensive immigration reform," she tweeted.