Mulvaney: Probing 2016 election was a factor in withholding Ukraine aid

Acting White House chief of staff Mick Mulvaney undercut President Trump's claim that there was no quid pro quo in the decision to withhold aid from Ukraine. Jeff Mason, a White House correspondent for Reuters, Amber Phillips, who covers Congress for the Washington Post, and Christina Ruffini, a CBS News foreign affairs reporter, spoke to CBSN's "R