Two important items:
1) Any polling about impeachment is not valid unless it takes place only in states with GOP senators. Seeing a 50/50 split means NOTHING when the sample grabs a lot of California. Only sampling in GOP senator states is meaningful to what is happening.
2) Why is asking for an investigation in another country something Democrats would oppose? If nothing is found and the country announces nothing was found, it would be helpful to Biden. So this posture of horror about asking for an investigation is misplaced. That investigation has as much chance to help Biden as hurt him, unless they know he’s dirty.