Asking A Foreign Government To Investigate Your Political Opponent

I don’t believe anyone, let alone a President Of the US, should ask a foreign government to investigate a political opponent for the purpose of winning an election. It doesn’t end there though, financial aid to fight their enemy and a White House visit was threatened to be blocked as an extortion attempt by the President. We have now seen ample evidence this really happened in the impeachment process. What are the republicans in the Senate thinking? Is this okay with them or do they just not care?