Overall, Republicans are more united as a party but face uncertainty and unease with the looming impeachment in the House. Democrats are in disarray because of an identity crisis of who and what they are as a party; many Democrats running for president have embraced a “Democratic socialist” agenda that quite possibly could turn into a Democrat/socialist candidate for president and party platform.
Add to this the fact that Democrats may have bitten off more than they can chew with impeachment. Should Democrats not impeach and just censure the president, they know President Trump will take a victory lap just as the 2020 campaign heats up. On the other hand, should the House impeach and the Senate not remove the president, that too could help Donald Trump, as he might be viewed by many voters as the victim of a political witch-hunt. The chances of the Senate removing the president, based on the evidence as it exists today, are slim and none. Thus, Democrats have more to lose from this folly.