WASHINGTON — Donald Trump says he’ll deliver a detailed speech Wednesday on his proposal to crack down on illegal immigration — but it’s anyone’s guess what he will say.

The announcement came late Sunday in a tweet by the Republican presidential nominee after days of wavering — and at least one canceled speech — on a question central to his campaign: Whether he would, as he said in November, use a “deportation force” to eject the estimated 11 million people in the U.S. illegally.

Trailing Democrat Hillary Clinton in many key states 10 weeks before the election, Trump is trying to win over moderate Republicans, some of whom have been turned off by his rhetoric on immigration and other issues. But any significant shift could disappoint his core supporters.

Trump’s immigration speech in Arizona will come after he and Clinton spent last week trading accusations on racial issues. Trump called Clinton “a bigot;” Clinton accused Trump of allowing hate groups to take over the Republican Party.

Clinton is starting this week by announcing her proposals for dealing with mental health issues. She is stressing the need to fully integrate mental health services into the U.S. health care system. Her plan stresses early diagnosis and intervention and calls for a national initiative for suicide prevention.

Immigration issues dominated the Sunday talk shows as Trump’s surrogates, led by running mate Mike Pence, discussed his approach. But none could address whether Trump still favored a deportation force.

They said Trump’s immigration policy will be humane, and insisted he has not been wavering on the issue. Any discussion of inconsistencies, they suggested, reflected media focus on the wrong issue.

Trump’s tweet Sunday suggested he was poised to clear up questions about his immigration stance.

Trump’s campaign also announced on Sunday a $10 million-plus buy for ads to air in nine competitive states starting Monday. And late Sunday, America’s only African-American owned and operated national Christian television network announced that its president and CEO, Bishop Wayne T. Jackson, would interview the Republican nominee Saturday in Detroit.