In this article by multiple reporters for The Washington Post, the Post reported that Trump doesn’t have a plan to relieve millions of Americans of crushing student loan debt and fears that Warren could defeat Trump with a progressive populist campaign:

President Trump is demanding aides present a plan to tackle student debt and the rising cost of a college education, worried that he has no response to expansive plans from Sen. Elizabeth Warren and other Democrats he may face on the ballot next year, several administration officials said.

[…]

The internal frustrations and failure to come up with a student debt plan are feeding the president’s anxieties that Democrats such as Warren will tap into populist impulses that propelled his 2016 victory, and that he will need policies beyond his signature areas of immigration and trade to counter them.