Congressional investigators want to question President Donald Trump’s longtime personal secretary as part of their ongoing probe into a controversial meeting between Trump campaign officials and a Russian lawyer promising dirt on Hillary Clinton, ABC News has learned.Rhona Graff, a senior vice president at the Trump Organization who has worked at Trump Tower for nearly 30 years, has acted as a gatekeeper to Trump. She remains a point of contact for the sprawling universe of Trump associates, politicians, reporters and others seeking Trump's time and attention, even now that he's in the White House.