The effort is aimed at calling attention during an election year to the massive amounts of spending by outside groups on the election. While President Obama and GOP presidential candidate Mitt Romney have both welcomed the help of super-PACs that can take unlimited political donations, their efforts are expected to give Romney a funding advantage.

“We recognize that you don’t win every fight in round one, and this is a fight worth continuing,” the Senate bill’s lead sponsor, Sen. Sheldon WhitehouseSheldon WhitehouseThis week: Democrats face fractures in spending fight McConnell seeks to divide and conquer Democrats On The Money: Democrats wary of emerging bipartisan infrastructure deal, warn of time crunch MORE (D-R.I.), said Monday in a statement.

“Putting an end to secret election spending by special interests is an essential step in protecting middle class priorities. For that reason, we are committed to continuing the debate on the DISCLOSE Act late into the night and asking for a second vote tomorrow if need be,” he said.

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Sen. Charles SchumerChuck SchumerIn Congress, what goes on behind closed doors? Senate Judiciary begins investigation into DOJ lawmaker subpoenas America needs a stable Israeli government MORE (N.Y.), the Democrats' messaging leader in the upper chamber, is leading the effort.

The legislation is a response to the Supreme Court’s 2010 Citizens United decision, which allowed unlimited and anonymous campaign contributions to outside groups. The groups are not allowed to be connected to a candidate’s campaign.

Democrats have argued that the Citizens United decision is anti-democratic because it allows corporations and the wealthy a greater say in elections without requiring those interests to publicly reveal their contributions.

“We believe that all of the unlimited cash allowed by the Citizens United decision must at least be disclosed,” Schumer said. “This legislation seeks to limit the damage of the Supreme Court decision that has given corporations and the very wealthy unprecedented sway over our elections, and represents one of the most serious threats to the future of our democracy.”

“We are determined to prove that transparency is not a radical concept,” said Sen. Tom UdallTom UdallSenate Democrats befuddled by Joe Manchin Study: Chemical used in paint thinners caused more deaths than EPA identified Oregon senator takes center stage in Democratic filibuster debate MORE (D-N.M.). “Our bill is as simple and straightforward as it gets — if you are making large donations to influence an election, the voters in that election should know who you are. The American people are blessed with common sense. They know that when someone will not admit to something, it is usually because there is something to hide.”

Other Democrats participating in the “vigil” are Sens. Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenPelosi: 'No intention' of abandoning Democrats' infrastructure goals McConnell seeks to divide and conquer Democrats Progressives want to tighten screws beyond Manchin and Sinema MORE (N.H.), Jeff MerkleyJeff MerkleyDemocrats mull overhaul of sweeping election bill Chicago police officer arrested for role in Capitol riot Democrats reintroduce bill to create 'millionaires surtax' MORE (Ore.), Michael BennetMichael Farrand BennetSenate panel advances nominations for key Treasury positions Democrats blast Biden climate adviser over infrastructure remarks Colorado lawmakers invite Harris to tour state's space industry MORE (Colo.) and Al FrankenAlan (Al) Stuart FrankenDemocrats, GOP face crowded primaries as party leaders lose control Gillibrand: 'I definitely want to run for president again' Maher chides Democrats: We 'suck the fun out of everything' MORE (Minn.).