Senate Democrats are investigating Donald Trump’s alleged quid pro quo offer to oil executives last month at a Mar-a-Lago fundraiser. Sen. Sheldon Whitehouse (D-RI) and Sen. Ron Wyden (D-OR) sent letters Thursday morning to top executives for eight oil companies and one trade group seeking more information about the April 11 dinner, where the former president reportedly offered to deliver their favored policies in exchange for $1 billion in campaign donations, reported the New York Times. “Time and time again, both Mr. Trump and the U.S. oil and gas industry have proved they are willing to sel…