A delegation of senators looked to up pressure on Russian President Vladimir Putin Saturday, as tensions around Ukraine heightened.

The eight lawmakers blasted the Russian leader while traveling through Ukraine and called Sunday's secession referendum in Crimea rigged and illegitimate. Some of the senators asked for the U.S. to provide military equipment to Ukrainian troops, and the group vowed crippling economic sanctions against Russia until the nation pulled back.

“This is the person that stated that the greatest catastrophe of the 20th century was the breakup of the Soviet Union,” said Sen. John McCainJohn Sidney McCainTrump informally offered Cohn CIA job before changing his mind: report Schiff: I thought more Republicans would speak out against Trump Trump presses GOP to change Senate rules MORE (R-Ariz.) of Putin. “We have to treat him for what he is. That does not reignite the Cold War, but it means we enact steps that make it clear ... that his ambitions will not be realized by the great community of nations that would resist him.”

“There’s one person I hold accountable for this aggression. It’s Vladimir Putin,” added Sen. Ron JohnsonRonald (Ron) Harold JohnsonSenate GOP shoots down bill blocking Trump tariffs Possible North Korea summit raises anxiety in Washington Wisconsin Republican would sign on to bill to nullify Trump tariffs MORE (R-Wis.). “If there’s further bloodshed, there’s also one person I will hold accountable.”

The bipartisan group hoped their presence in Ukraine would underline the united support the U.S. is providing to the nation, ushering in a new government while Russian forces are amassing along its border.

“We are standing here united,” said Sen. Chris MurphyChristopher (Chris) Scott MurphySenate tees up Yemen vote for Tuesday Congress moving to end US involvement in Yemen This week: Congress races to prevent third shutdown MORE (D-Conn.). “There will be consequences for the actions that have already been taken ... there’s a price to be paid for this type of aggression.”

The other senators in the delegation were Sens. Dick DurbinRichard (Dick) Joseph DurbinTrump vows tougher borders to fight opioid epidemic Clinton: 'I meant no disrespect' with Trump voter comments Lawmakers rally to defend Mueller after McCabe exit MORE (D-Ill.), Sheldon WhitehouseSheldon WhitehouseOvernight Energy: Zinke grilled on travel, offshore drilling plans | Pruitt says California can't dictate emissions standard | Dems sound off on elephant trophy policy Overnight Energy: Dems probe EPA security contract | GAO expands inquiry into EPA advisory boards | Dems want more time to comment on drilling plan Opioid crisis spurs Medicaid funds push MORE (D-R.I.), John BarrassoJohn Anthony BarrassoSenators target 'gag clauses' that hide potential savings on prescriptions USPTO needs to be forced to do its job and reject bad patents Senate Dems propose tax cut rollback to pay for infrastructure MORE (R-Wyo.), John HoevenJohn Henry HoevenTrump’s economic policies spur GOP angst Crop sale incentive program is wrong policy for trade and security Sen. Steve Daines knows the ski slopes, residents MORE (R-N.D.) and Jeff FlakeJeffrey (Jeff) Lane FlakeSenate GOP: Legislation to protect Mueller not needed Trump prepared to hit China with B in annual tariffs: report White House, Democrats reject competing DACA offers MORE (R-Ariz.).

While McCain and Durbin have backed sending weapons to Ukraine, no senator suggested that the U.S get directly involved in a military response.

The group dismissed the legitimacy of Sunday’s election on the future of Crimea, as McCain called it “phony” and Durbin described it as “Soviet-style.”

Their criticism came shortly after Russia vetoed a United Nations resolution condemning the referendum. China abstained from the vote, but all other voting nations backed it.