Senate Majority Leader Mitch McConnell (R-Ky.) is pulling out all the stops to make sure not a single Republican senator backs the campaign finance and ethics reform bill that House Democrats are set to pass on Friday.

McConnell, a longtime opponent of campaign finance reform who battled the late Sen. John McCain (R-Ariz.) over the issue, made clear in December that the House proposal would never see floor time in the Senate.

He's continued to pummel the legislation, sending a stern warning to any GOP colleague who may be thinking about supporting it.

"This is an issue that I've dealt with for decades," McConnell said at a press conference with Senate and House GOP colleagues on Wednesday. "This is a terrible proposal, it will not get any floor time in the Senate.

"For myself, I don't see anything in here salvageable," he added. "This is a solution in search of a problem. What it really is is a bill designed to make it more likely Democrats win more often."

A senior Republican aide described McConnell as making a "full tilt" effort to quash the House bill. White House counsel Don McGahn spoke to the Senate GOP conference Wednesday to explain why it would be a mistake for any Republican to support it.

Despite the GOP leader's efforts, Senate Democrats feel confident they can pick off some members of his conference.

"There are pieces of it that many senators and House members have been working on for a long time, whether it's making voting easier, whether it's taking the dark money and big money out of politics, or whether it's government ethics, there are a number of senators who have almost identical parts of their bills in this bill," Sen. Tom Udall (D-N.M.) said of the House legislation, known as H.R. 1.

Udall plans to introduce a companion Senate bill next week.

He says it will be "very difficult" for McConnell to keep his GOP conference unified "based on the history of how Republicans have responded individually to a lot of these issues."

Two possible swing players in the Senate, Sens. Cory Gardner (R-Colo.) and Susan Collins (R-Maine), declined to comment Thursday on the House bill.

Udall thinks his GOP colleagues, several of whom face tough reelection races next year, are nervous about the deluge of outside money that is about to pour into their home states.

"The more those dark money numbers grow, the more people see these attacks. If you've been in a campaign where you've had tens of millions of dollars spent in dark money against you -you talk to Republican members, and they say this isn't right," Udall said.

One component of the House bill, the Honest Ads Act, requires social media companies such as Facebook to disclose who is paying for political ads on its platform.

That language reflects a bill introduced in the last Congress by Sens. Amy Klobuchar (D-Minn.) and Mark Warner (D-Va.). It attracted the support of McCain.

Another piece of the bill, the Disclose Act, resembles legislation that Sen. Lisa Murkowski (R-Alaska) sponsored with Sen. Ron Wyden (D-Ore.) in 2013, the Follow the Money Act. It would have required the Federal Election Commission to establish a real-time reporting system for contributions to candidates' campaigns and independent spending efforts.

Murkowksi did not vote when the Disclose Act failed to overcome a 60-vote procedural hurdle in September of 2010 and July of 2012, but she spoke "kindly" about the bill, according to Sen. Sheldon Whitehouse (D-R.I.), one of its backers.

Asked Thursday if she could support legislation to require more disclosure of donors to independent political spending groups, Murkowski replied, "I have in the past said that these are issues that are ripe for review."

"Is it appropriate for more disclosure, generally, and quicker? Yes," she added.

A third component of the House-passed reform bill would attempt to slow the flow of foreign money into elections by cracking down on the use of shell corporations to hide political spending from overseas sources. That idea has support from Senate Judiciary Committee Chairman Lindsey Graham (R-S.C.).

"We're going to have a hearing about how foreign entities, the dark money stuff," influence elections, Graham said Thursday.

"It's so easy to set up a corporation in America and funnel money through it to affect a campaign," he added, noting that Whitehouse "has got legislation about making sure that these shell corporations are harder to set up."

"It's just a matter of time and it's probably already happened where some foreign entity has used our system against us," Graham added.

Another key piece of H.R. 1 would support a constitutional amendment to overturn Citizens United v. Federal Election Commission (FEC), the landmark Supreme Court ruling that overturned campaign finance restrictions on corporations and labor unions, enabling outside groups to spend hundreds of millions of dollars to influence federal races.

Historically, a constitutional amendment to give Congress authority over campaign finance law without interference from the courts has enjoyed Republican support.

McConnell is trying to keep his colleagues in line by arguing that Republicans should use the House bill as ammo against Democrats in the 2020 elections.

"I believe we can actually win elections against people who vote for this turkey," he said Wednesday.

He highlighted its most controversial elements, such as public financing for presidential and congressional candidates that would have the federal government provide matching funds from voluntary donors.

He also cited a proposal to restructure the FEC into a five-member commission that would be controlled by the president's party.

McConnell has a long record opposing campaign finance efforts. He took the lead in the Senate opposing the McCain-Feingold campaign reform push of 2001 and 2002, which resulted in the Bipartisan Campaign Reform Act and banned national political parties from raising and spending unlimited funds known as soft money.

He also served as the lead plaintiff in the lawsuit that attempted to overturn that law, McConnell v. FEC, which the Supreme Court upheld in 2003.

The House bill also includes several ethics and election reform components, such as a requirement that the president and vice president disclose years of their tax returns and to enhance election security by requiring the director of national intelligence to report on attempts of foreign interference.