The White House on Sunday was quick to dismiss the referendum.
The administration called on others in the international community to impose costs on Russia.
"Clearly he has set the table to his advantage in any negotiation going forward," he said.
“This is a Soviet-style election. We know what the end is going to be,” Durbin said.
“This sham referendum isn’t fooling anyone,” he said.
“Putin only understands strength,” Sen. Robert Menendez said.
"We used to call it plebiscite in the days of Hitler and Stalin," he said
Ukrainian foreign ministry alleged 80 Russian forces invaded a village just north of Crimea.
Russia vetoed a U.N. Security Council resolution against Sunday's referendum in Crimea.
The vice president will discuss Ukraine's unrest with European leaders.