Senator Sheldon Whitehouse, a Rhode Island Democrat, has threatened former President Donald Trump with a new investigation into his reported promises to Big Oil. The Washington Post reported this week of a deal that Trump, the presumptive GOP presidential nominee, reportedly offered to top oil executives at a Mar-a-Lago dinner last month—raise $1 billion for his campaign and he will reverse dozens of President Joe Biden's environmental regulations and prevent new rules, according to people with knowledge of the dinner. According to the Post's sources, Trump said gifting him $1 billion would be a "deal," because of the taxation and...