Any evangelical that allows “Abortion on Demand” democrats to be elected in the next election loses their right to say they are pro-life.
No evangelical can do that except for voting for a candidate who espouses such a thing.
Voters don't "allow" anything. We vote for a candidate, plain and simple. If we don't think he's trustworthy, if we don't believe he will be a good leader, then we shouldn't vote for him no matter what letter comes after his name on the ballot.
Voting against the Democrat agenda whenever possible is a given. In the general election, we can talk about making such a compromise. But now? In the primaries? It is far too early in this process to panic.