Efforts to downsize the U.S. Postal Service will face a series of hurdles today when the Senate votes on up to 39 amendments to the chamber’s postal reform bill, including a proposal to limit spending on government conferences in the wake of the recent General Services Administration scandal.

“I hope once we work through the amendments … we will see a strong bipartisan vote to modernize the Postal Service and save this important institution from insolvency,” Senate Majority Leader Harry Reid (D-Nev.) said, adding that he expects the measure to pass.

The USPS, with about 570,000 employees, is the second largest civilian employer after Walmart. But with the increase in paperless communication and a commensurate decline in mail volume, the agency projects a $14.1 billion net loss for fiscal 2012.

Senate Homeland Security and Governmental Affairs Chairman Joe Lieberman (I-Conn.), who is a sponsor of the bill, said he does not expect to hold recorded votes on all amendments, but voting could still take up most of the day.

“We expect that probably more than half of [the amendments] will be negotiated to agreements, modified [or] accepted, but there still will be a significant amount of roll call votes,” Lieberman said on the Senate floor.

One amendment that is on track to be cleared, possibly by voice vote, is a proposal from Sen. Tom Coburn (R-Okla.) that would limit government conference spending, which could save more than $65 million a year, according to Coburn’s office.

The amendment comes after the General Services Administration was found to have spent more than $800,000 on a now-infamous conference in Las Vegas. The scandal has triggered a raft of Congressional investigations, and Senators see the amendment as an opportunity to signal their disdain for the GSA’s overspending.

The Coburn amendment would reduce the amount an agency may spend on conferences to 80 percent of the amount spent in 2010 and cap the amount that may be spent on a single conference at $500,000, unless the agency is the primary sponsor.

The amendment would also allow non-federal foundations to provide financial support for a conference, but would require a listing of such sponsors and a certification that there is no conflict of interest resulting from support received from each. It would prohibit sponsoring more than one conference per year per organization.

The Coburn proposal would further limit to 50 the number of employees from a single agency traveling to an international conference.

Lieberman said on CBS’ “Face the Nation” on Sunday that it is “a very good amendment” but that he wants to “tweak parts of it.”

Along with the Coburn amendment, the Senate will also vote on a substitute amendment offered by Sen. John McCain (R-Ariz.). The bill would replace the Senate measure with the House version of the reform bill. The House bill would set up a board to oversee the USPS and expedite measures to cut costs.

Other proposals that will be considered today include an amendment from Sen. Barbara Mikulski (D-Md.), who is fighting to keep a mail-processing center open in Easton, Md.

Her amendment would require a governor’s certification to close a postal facility. The governor would have to certify that the proposed closing or consolidation would not harm community safety, would not directly or indirectly disrupt commerce, and would not limit access to communications in any rural community that lacks broadband Internet availability or cellphone coverage.

Sen. Tom Udall (D-N.M.) is offering a proposal that would allow the USPS to continue Saturday delivery. The current bill would reduce post office service to five days per week within two years.

Udall said he believes that the current schedule is a significant competitive advantage for post offices and is an essential service for communities and businesses. Saturday service also supports nearly 80,000 jobs nationwide.

On the other side of the issue is Sen. Bob Corker (R-Tenn.), who is offering an amendment that would immediately scale back mail service to five days a week if USPS management decides to do so.

Sen. Jon Tester (D-Mont.) is offering an amendment that would cap the salaries of the top six postal employees at $200,000 a year. The postmaster general, for example, makes about $400,000 a year in salary and benefits.

“The Postal Service is public service,” Tester said in a release last week. “And there’s no reason folks at the Postal Service should be making more than the Defense Secretary — especially if they’re turning to rural communities for cuts.”

Sen. Rand Paul also is looking to rein in executive pay at the USPS. The Kentucky Republican has offered an amendment that would provide performance-based pay for the postmaster general and would limit the authority of the agency to award bonuses.

Senate Budget ranking member Jeff Sessions (R-Ala.) said he intends to raise a point of order against the bill for adding to the deficit, which will need 60 votes to be defeated.

But under the agreement teeing up the votes, all amendments would need 60 votes, and the bill would need 60 votes for final passage. So the Sessions amendment is not expected to prevent the bill from passing.

Clarification: 9:13 a.m., April 24

This article was updated to specify that Sen. Bob Corker’s amendment would scale back mail service only if USPS management decides to do so.