U.S. President Donald Trump is expected to announce on Thursday his plans to automatically deny asylum to migrants who try to enter the U.S. illegally between ports of entry — part of his latest election-season response to caravans heading toward the border.

On Wednesday, Trump doubled down on promoting the conspiracy theory that George Soros may be behind the caravan of migrants coming into the U.S. When asked by a reporter directly if Soros was funding the caravan, Trump responded, "I don't know who, but I wouldn't be surprised. A lot of people say yes."

Trump's comments coincide with a series of actions he has taken ahead of the U.S. midterm elections aimed at cracking down on immigration into the U.S. - which included an ad that many critics blasted as racist.

It was unclear whether the restrictions Trump was expected to propose would apply only to those traveling in the caravans or extend to all people trying to enter the country. And it also was unclear whether Trump has the legal authority to change the rules.

The asylum clause of the Immigration and Nationality Act notes that anyone who arrives to the U.S. may apply for asylum. And any change would almost certainly be immediately challenged in court.

Trump was to make his announcement during brief remarks Thursday afternoon, according to three people familiar with the plans. They spoke only on condition of anonymity because they were not authorized to speak publicly by name.

The administration has been discussing various options to address the caravans for days and it was possible that things could change before Trump’s 4:15 p.m. remarks “on the illegal immigration crisis” before he departs the White House for a campaign rally in Missouri.

It was unclear whether the restrictions Trump was expected to propose would apply only to those traveling in the caravans or if they would extend to all people trying to enter the country.

It also was unclear whether Trump has the legal authority to change the rules. The asylum clause of the Immigration and Nationality Act notes that anyone who arrives to the U.S. may apply for asylum. And any change would almost certainly be immediately challenged in court.

The announcement would be Trump’s latest attempt to keep the issue of immigration front-and-center as he tries to drum up GOP enthusiasm in the final stretch before next Tuesday’s elections, which will determine whether the GOP retains control of Congress. Trump and his aides have long believed the issue is key to turning out his base, and Trump has seized on the caravans of Central American migrants slowly making their way through Mexico toward the U.S.

Trump and other administration officials have long encouraged those seeking to claim asylum to come through legal ports of entry. But many migrants are unaware of that guidance, and official border crossings are often clogged with people. Backlogs have grown especially bad in recent months at crossings in California, Arizona and Texas, with people generally waiting five weeks to claim asylum at San Diego’s main crossing and sleeping out in the open for days at a time.

Migrants who cross illegally are generally arrested and often seek asylum or some other form of protection. Claims have spiked in recent years, and there is currently a backlog of more than 800,000 cases pending in immigration court. Administration officials have railed against what they say are loopholes designed to encourage people, especially from Central America, to come to the U.S. and claim asylum. Generally, only about 20 percent of applicants are granted asylum.