(J. Scott Applewhite/Associated Press)

On Tuesday, the Senate is set to vote on up to 38 amendments to a major bipartisan bill that would reform the Postal Service, including proposals to end six-day mail delivery, continue six-day mail delivery, require USPS to wait two more years before closing small rural post offices, and to close post offices on Capitol Hill.

As we’ve noted before, the issue is tricky to track because it doesn’t break down along traditional partisan or ideological lines. Instead, postal reform pits lawmakers from smaller rural states against colleagues from larger, more urban areas. Lawmakers who normally work closely together — such as Sens. Joseph I. Lieberman (I-Conn.) and John McCain (R-Ariz.) — are on opposing sides of the issue.

Senate leaders may trim the list of amendments to 20 or fewer by votes beginning Tuesday. Lieberman, Senate Majority Leader Harry M. Reid (D-Nev.) and Sen. Susan Collins (R-Maine) negotiated late last week to permit votes on the amendments as a way to keep skittish colleagues happy and to allow at least a few of them the opportunity to say they tried to protect small post offices, the concerns of senior citizens and home-state businesses that rely on or profit from the mailing industry. (We wrote more on this issue in Friday.)

After postal reform, the Senate is slated to move to reauthorize the Violence Against Women Act, which is set to expire at the end of May.

In the House, lawmakers plan to vote Tuesday on a series of bills that would swap federal land from one agency to another, or release some federally protected property for private development. Later in the week, the House plans to vote on the DATA Act, which would establish an independent board to track all federal spending. It also would require agencies to report data in a standardized format. The legislation, introduced by Rep. Darrell Issa (R-Calif.) in the House and Sen. Mark R. Warner (D-Va.), in the Senate, is expected to earn more support because Issa and Warner are casting it as the type of measure that can help prevent scandals such as the one plaguing the General Services Administration.

Cybersecurity is another issue that House lawmakers plan to consider this week when they vote Thursday on a bill that would encourage companies to share information about cyber threats, but critics say it might lead firms to share private user information with other companies or spy agencies. The White House is critical of the bill, saying it should include stronger privacy protections.

Secret Service, GSA scandal fallout continues

The House Homeland Security Committee expects a full accounting of the Secret Service’s ongoing investigation by Friday. Over the weekend, Chairman Peter T. King (R-N.Y.) sent a letter to Secret Service Director Mark Sullivan asking for “the specific facts surrounding the alleged incident in Colombia, the conditions that allowed it to happen, and what is being done to ensure this never happens again in the future.” King’s letter includes 50 questions, including how many agency employees paid prostitutes, whether agency property was stolen, whether there were “no-go” areas in and around Cartagena where the alleged prostitution scandal unfolded, and the CIA’s counterintelligence assessment of Colombia.

Meanwhile, Homeland Security Secretary Janet Napolitano is set to testify Wednesday before the Senate Judiciary Committee to discuss general DHS oversight matters, including the Secret Service scandal.

As for the GSA spending scandal — what many lawmakers consider to be the more serious case — more congressional subcommittees are expected to hear from agency officials this week, while the Senate Homeland Security and Governmental Affairs Committee also plans to look into broader concerns about the agency’s spending habits in the coming weeks.

The 'veepstakes' on Capitol Hill

Sen. Marco Rubio once again dodged questions Sunday about whether he would serve as Republican Mitt Romney’s vice presidential running mate and suggested that his fellow Floridian Jeb Bush might be a better pick. (But conservative columnist George Will said Sunday that he doesn’t like that idea.)

“I think from this point moving forward, I think it’d be wise for all Republicans to kind of respect that process, myself included, and say moving forward, we’re going to let his process play itself out,” Rubio told CNN’s “State of the Union” on Sunday. He added: “The last thing he needs are those of us in the peanut gallery to be saying what we would or would not do.”

Other GOP lawmakers are facing the VP — Sen. Rob Portman (Ohio) and Reps. Paul Ryan (Wis.) and Cathy McMorris Rodgers (Wash.), among others — and time will tell whether they or media reports reveal who is under consideration for the No. 2 slot.

And finally . . .

Make sure to read these two important dispatches from 2chambers colleagues Paul Kane and Rosalind S. Helderman:

Kane reports on a new book by Robert Draper that provides a telling account of how freshmen Republican lawmakers “caused feuds among [House Speaker John A.] Boehner and his lieutenants that led some to fear a mutiny, heightened several showdowns with President Obama and eventually led to fissures among the rookies, pitting those who seldom trusted the leaders against those who reflexively did.”

And Helderman writes from Missouri, where Sen. Claire McCaskill (R-Mo.) “is betting she can turn the millions spent against her into an advantage, a sign of her political independence. She devoted her first campaign ad for reelection to the argument that out-of-state special interests are trying to knock her out of the Senate in November.”

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