trump long who has a conscious and who has character and who believes in ethics. i think that is probably why dowd left and why ty cobb left and why mr. flood s time is limited. reporter: the president s latest tweets are a sign his legal team is getting more aggressive. hinting he could shut down the investigation mr. trump tweeted, at some point i will have no choice but to use the powers granted to the presidency and get involved. the president is escalating his attack on the justice department after mueller warned this year he may subpoena mr. trump to force testimony. and democrats argue a subpoena may be necessary. do i want to see it? no. but if it is necessary, it should be done. what would plaq would make necessary. if he refused to answer the questions the special counsel deems to be answered. reporter: rod rosenstein told laura jarrett the investigators are not backing down. there have been people who have been making threats, privately and publicly against me f