Oprah appeals to the more liberal minded people. But if you want Trump gone, we need someone that will appeal to the moderate and conservative-light people. Obviously the liberals are going to vote for the Democrat whoever it is. But the moderates and conservative-light people need to be won over.
Alternatively, and probably more easily; get someone that actually excites the liberal base—get the non-voters to go out and vote. Going right isn’t always, or even usually, the answer.
the liberals alone can’t elect a President.
They can if all of them vote. Let’s say, hypothetically, that the country has an even 50/50 split between liberals and conservatives. The 20XX election rolls around, and neither liberals or conservatives are too happy about their choices; so there’s only a 50% voter turnout, with half of the votes being for the left-leaning candidate and the other half for the conservative. If the liberals were excited about their candidate, then more would go out and vote, tipping the election towards the left-wing candidate.
I think it’s much easier to get those non-voters to vote than to try and win over moderates and right-wingers. Besides, the Democrat party is already trying too hard to win moderates and right-wingers over, and they lost their identity in the process. There is no liberal party in America.