House investigators said they have uncovered evidence that White House officials became personally involved in an Energy Department review of a hot-button $535 million loan guarantee to the now-failed California solar company Solyndra…

Thursday’s letter, which calls on the White House to turn over correspondence between administration officials, Solyndra and its investors, presents the most pointed suggestion that the White House had direct involvement in the financing.

“How did this company, without maybe the best economic plan, all of a sudden get to the head of the line?” Upton told ABC News in an interview this week. “We want to know who made this decision … and we’re not going to stop until we get those answers.”