Prove it.
To denounce a candidate is to say that you shouldn’t vote for them. To vote for a candidate who you say doesn’t deserve a vote is self-contradiction.
Define “tactically correct”.
A tactically correct action is an action that best furthers your goals.
To denounce a candidate is to say that you shouldn’t vote for them.
Or you can vote against them.
To vote for a candidate who you say doesn’t deserve a vote is self-contradiction.
They deserve a vote solely for the reason that doing so is the only possible means of voting against the other candidate. It’s not a self-contradiction.
A tactically correct action is an action that best furthers your goals.
What are the goals in this scenario?