The op-ed Rep. Rashida Tlaib wrote explaining why she thinks Trump should be impeached – published before the “motherfucker” controversy – is worth reading. This is her response to the standard Dem line, which is “wait for Mueller.”
for what it's worth, I think Tlaib made a fairly strong case for impeachment here, and expressing it at a rally as "impeach the motherfucker" undermines her own case