Democrats in the Senate would lose either way. Those that vote to impeach him will damage the reputation of the Democratic party and those that don't impeach him will damage their own reputation.
He still needs to be given some time to step up and do something, though. If thousands more show up in the next month, and he still makes excuses, then that would be the time to impeach. Additional charges could then be leveled at him and the impeachment itself would give more exposure to all those other offenses he's guilty of.
His impeachment is not about the immigration scam.
It is about his aiding and abetting our enemy in time of WAR.
He armed and supported al Qaeda. In Libya, Syria, Turkey, Iraq.
Last time I looked Treason is still defined clearly in the Constitution. And the penalty for Treason is serious.