Billionaire businessman and philanthropist David Koch has pledged “tens of millions of dollars” to help bankroll the campaign of Libertarian presidential candidate Gary Johnson, according to a source within Johnson’s campaign. Koch’s money will be made available should Johnson, a former two-term Republican governor of New Mexico, secure his second consecutive Libertarian Party presidential nomination, the source said. The Libertarians will select their presidential ticket during the party’s national convention later this month in Orlando.