Syndicated political columnists often use their newspaper columns to try to persuade readers to vote a certain way.
Evidence
Syndicated political columnists often use their newspaper columns to try to persuade readers to vote a certain way.
By the time such a column appears, nearly all who will vote in the election will have already made a decision about which candidate to vote for.
Conclusion
However, their efforts to persuade voters rarely succeed.
Evaluate
The argument assumes that anyone who has made a decision about which candidate to vote for cannot be persuaded to vote a different way.