Former Bill Clinton pollster Mark Penn criticized Democrats on Friday for trying to thwart former independent presidential candidate Robert F. Kennedy’s efforts to get on the ballot before he endorsed former President Donald Trump. Kennedy announced he was suspending his presidential campaign on Aug. 23 and endorsed Trump. He has since sought to remove his name from several state ballots. Penn said that Democrats initially had tried to keep Kennedy off ballots but are now trying to keep him on to pull support away from the former president. Read: Columbia Protester Who Demanded ‘Humanitarian A…