Oil tycoon Tim Dunn has spent millions to try to bend Texas toward his conservative politics. Now, as he considers bids for his drilling company that’s said to be valued at more than $10 billion amid a merger-mania in the shale patch, Dunn is poised for a windfall that could dramatically boost his giving – and his influence.

The head of CrownRock LP is a devout Christian who has bankrolled candidates and groups that favor book bans and a private-school voucher system. He is a patron for immigration hardliners who have pushed to block asylum-seekers from crossing the US southern border.