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.

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“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 McCainSenate's defense authorization would set cyber doctrine Senate Dems hold floor talk-a-thon against latest ObamaCare repeal bill Overnight Defense: Senate passes 0B defense bill | 3,000 US troops heading to Afghanistan | Two more Navy officials fired over ship collisions 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 Dems hold floor talk-a-thon against latest ObamaCare repeal bill Sen. Cassidy plans to bring down Medicaid Senate committee schedules hearing on health care block grants 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 Dem: Graham-Cassidy is an 'intellectual and moral garbage truck fire' Dems call for action against Cassidy-Graham ObamaCare repeal Murphy fires back at Trump on filibuster 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 DurbinSenate Dems hold floor talk-a-thon against latest ObamaCare repeal bill Overnight Defense: Senate passes 0B defense bill | 3,000 US troops heading to Afghanistan | Two more Navy officials fired over ship collisions Senate passes 0B defense bill MORE (D-Ill.), Sheldon WhitehouseSheldon WhitehouseJuan Williams: Momentum builds against gerrymandering Overnight Regulation: FTC launches probe into Equifax | Dems propose tougher data security rules | NYC aims to slash greenhouse gas emissions | EPA to reconsider Obama coal ash rule Overnight Cybersecurity: Kaspersky to testify before House | US sanctions Iranians over cyberattacks | Equifax reveals flaw that led to hack MORE (D-R.I.), John BarrassoJohn Anthony BarrassoDems force 'Medicare for All' on Americans but exempt themselves GOP sees fresh opening with Dems’ single payer embrace Overnight Health Care: CBO predicts 15 percent ObamaCare premium hike | Trump calls Sanders single-payer plan ‘curse on the US’ | Republican seeks score of Sanders’s bill MORE (R-Wyo.), John HoevenJohn Henry HoevenAir Force One is Trump’s new boardroom Overnight Finance: Trump strikes debt, spending deal with Dems | Deal shocks GOP | Fed’s No. 2 to resign | Trump keeps tax squeeze on red state Dems | House aims to pass budget next week Trump praises Dem senator during tax speech MORE (R-N.D.) and Jeff FlakeJeffrey (Jeff) Lane FlakeCorker pressed as reelection challenges mount -trillion debt puts US fiscal house on very shaky ground Senate votes down Paul's bid to revoke war authorizations 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.