Christian prophets must speak out against evil, always. But they must speak out against evil on every side of the political spectrum. If they back one side, they lose their credibility.
But prophets should not appoint kings. They should speak against evil, but be careful about claiming that a new person or party is God’s answer.
The problem is that all political leaders are controlled by the spiritual principalities and powers in the spiritual realms that dominate their nation. That is why they always disappoint. They rarely start out as evil. Most begin with good intentions, but once they gain power, they come under attack by the principalities and powers and become evil themselves. This is why most political leaders usually end up being just like their predecessors, even if they are from the other side.
And if the prophets have symbolically anointed the new leader, they will find it hard to critique them, because they will feel loyal to their selection.
Political power is a false gospel. The kingdom of God will not come in fullness until the god of political power has fallen. But God will not allow it to fall, until has people are prepared to bring in a kingdom based society that is a real alternative.
When Christians vote in elections, they are submitting to the principalities and powers that control the state.
Prophetic people would be better not to vote, as it would be a step towards getting free from the control of these powerful spiritual forces.
If they can get free, they could become prophets to their nation.