While UK Prime Minister Boris Johnson braces for more potential resignations following Tuesday's high-profile departures, another threat to his premiership is the prospect of his opponents within the Conservative Party taking control of the critical 1922 Committee of backbench MPs and changing party rules to allow another confidence vote in him. Speaking on Bloomberg Television, John Curtice, professor of politics at University of Strathclyde and a polling expert, says that the "mood music" has turned on Johnson and that there is now a body of Tory MPs who are "no longer willing to defend him" despite supporting him in last month's confidence ballot.