The house, I can't give names. Usually there are always a couple, three, four who don't follow the party line. I think Democrats Jones and Manchin could very well vote to acquit. Jones, Alabama is up for reelection in a state where Trump has a 60% approval rating. Manchin, not up, but 61% of West Virginians approve of Trump.
Republicans other than Murkowski who doesn't like Trump, you have Gardner, Colorado, Collins, Maine and Ernst, Iowa who are up for reelection in light blue states where Trump's approval is at or near 40%. Those three are between and rock and a hard place. To have a decent chance at winning in the general, they probably have to vote AYE to convict and remove. But that means all three would probably be primaried out by Trump supporters. If they vote NAY, vote to acquit Trump, they're all probably dead meat in the general election.
Romney, I never considered him. Perhaps I should. Regardless, there you have your 4-5 GOP senators who could vote to convict. What everyone ignores is you very well could have two Democrats voting to acquit. If Jones and Manchin do, they will be voting in accords to their constituents wishes. That also gets lost in the shuffle. How the people in all these different states view Trump and whether or not they want him removed or to stay.