Maybe he would have vetoed the Dem bill if he had gotten a chance- he didn’t
He’s referring to a 2018 bill backed by Senate Democrats and a few Republicans that would have provided $25 billion over a decade to significantly expand the wall and fund other programs to improve Southern border security.
Trump vehemently opposed the bill and threatened to veto it because it did not contain two immigration reforms he demanded: ending the visa lottery and deeply restricting family-based immigration.
We quibble, however, with Kaine’s use of the term "deal," which suggests everything was guaranteed for passage if the president went along. Republicans lawmakers never made that promise. It was really a proposal.
Link: https://www.politifact.com/virginia/statements/2019/jan/15/tim-kaine/tim-kaine-mostly-accurate-about-trump-nixing-25-bi/