In the 1970s, a single recording of the President's Chief of Staff, Haldeman suggesting that the President could order the C.I.A., to order the Justice Department, to halt the Watergate investigations to which, Nixon said "Uh Huh", was enough for Republicans to tell Nixon to either resign or face impeachment in the House. Nixon resigned rather than face impeachment. Nixon did not need to specifically say "Yes" to acquiesce.
In the 1990s, a legalism, offered by Bill Clinton in a deposition, as to the legal meaning of sexual relations, in a private matter not involving the office of the Presidency, was not sufficient for a Republican majority to not impeach the President. He was impeached.
In 2017, the President informed the Director of the F.B.I. that "hoped the Director would let the Flynn investigation go". Although his intent was clear and has, since, been bolstered by claims that Trump tried to get other agencies of the intelligence service to also bring pressure to bear to stop the investigation, Republicans now are parsing the word "hope" claiming that the Unitary Executive, Trump, would need to to use another word to merit impeachment.