WASHINGTON — President Donald Trump started a Twitter war with Sen. Kirsten Gillibrand on Tuesday, calling her a "lightweight'' and "flunky'' to Senate Minority Leader Charles E. Schumer, claiming "she would do anything for'' campaign contributions.But Gillibrand shot back on Twitter, calling him unfit for the presidency. And critics suggested the President's "do anything" for a donation remark was an effort to "slut-shame" the New York Democrat.