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If you believe that a president should not use foreign policy to advance his own personal agenda, then you must support his impeachment. Waiting for the election will only convince President Trump that what he did in withholding monies appropriated by Congress for the Ukraine was OK.
The argument that President Trump did not, in the end, get what he wanted from Ukraine is invalid, since the asking was in itself illegal and the monies were only released after the White House learned of the whistleblower's report.
Congressional Republicans are not doing this country a favor by pretending President Trump did nothing wrong.