Senate Majority Leader Mitch McConnell has bolstered attempts to “delegitimize” President-elect Trump’s victory by backing calls for a congressional probe into Russia’s hacking-related activities during the 2016 presidential election, a Trump transition official said Monday.

“I think what this is is an attempt to delegitimize President-elect Trump’s win,” Trump transition spokesman Jason Miller said of the calls for a congressional investigation into Moscow’s alleged interference in the election when asked about McConnell’s support for it.