Republicans and Democrats will put good will to the test when Congress returns this week to potentially incendiary fights over nominations, unresolved disputes over student loans and the farm bill, and the uncertainty of whether lawmakers have the political will to rewrite the nation's immigration laws.
The cooperation evident in the Senate last month with passage of a bipartisan immigration bill could be wiped out immediately if Majority Leader Harry Reid, D-Nev., frustrated with GOP delaying tactics on judges and nominations, tries to change the Senate rules by scrapping the current three-fifths majority for a simple majority.
Republican leader Mitch McConnell of Kentucky has indicated it's a decision Reid could regret if the GOP seizes Senate control in next year's elections.
"Once the Senate definitively breaks the rules to change the rules, the pressure to respond in kind will be irresistible to future majorities," McConnell said last month, looking ahead to 2014 when Democrats have to defend 21 seats to the GOP's 14.
McConnell envisioned a long list of reversals from the Democratic agenda, from repealing President Barack Obama's health care law to shipping radioactive nuclear waste to Yucca Mountain in Reid's home state of Nevada.
Recently elected Democrats have clamored for changes in Senate rules as Obama has faced Republican resistance to his nominations.
Two Cabinet-rank choices - Tom Perez as labor secretary and Gina McCarthy to head the Environmental Protection Agency - could be approved by the Senate this month after a loud debate over administration policies.
The GOP also has challenged Obama's three judicial nominees to the powerful U.S. Court of Appeals for the District of Columbia Circuit as they've tried to eliminate the vacancies.
Reid had served notice in April that the Democratic majority could change the Senate rules on "any given day," and he was willing to do so if necessary.
In the Republican-controlled House, courteous behavior, even within the GOP ranks, has barely been perceptible with the ignominious failure of the farm bill. Some collaboration will be necessary if the House is to move ahead on immigration legislation this month.
Conservatives from safe, gerrymandered House districts have rebuffed appeals from some national Republicans who argue that embracing immigration overhaul will boost the party's political standing with an increasingly diverse electorate, especially in the 2016 presidential election. The conservatives strongly oppose any legislation offering legalization to immigrants living here illegally.
Reflecting the will of the rank and file, House Speaker John Boehner of Ohio and other Republicans have said the comprehensive Senate immigration bill that couples the promise of citizenship for those living here unlawfully with increased border security is a nonstarter in the House.
Republicans were assessing the views of their constituents during the weeklong July Fourth break and planned to discuss their next steps at a private meeting Wednesday.
"I think what members need before we proceed on the actual immigration reform is an ironclad guarantee that the border is going to be secure," Rep. Matt Salmon, R-Ariz., said just before the recess. He didn't see any urgency to acting quickly.
"I find it very interesting the argument that we can't wait till the border is secure, we can't even do a six-month test to make sure ... we have to get them out of the shadows immediately," Salmon said. "They've been in the shadows for 20 years, and another six months is going to break their backs? I mean come on, that's not even a valid argument."
The House Judiciary Committee has adopted a piecemeal approach, approving a series of bills, none with a path to citizenship that Obama and Democrats are seeking. Democrats hope the single-issue bills get them to a conference with the Senate, where the prospects for a far-reaching overhaul improve.
A more pressing concern for some lawmakers was the fate of the five-year, half-trillion-dollar farm bill.
In a surprise last month, the House rejected the bill as 62 Republicans voted no after Boehner had urged support for the measure.
House conservatives wanted cuts deeper than $2 billion annually, or about 3 percent, in the almost $80 billion-a-year food stamp program while Democrats were furious with a last-minute amendment that would have added additional work requirements to food stamps, now called the Supplemental Nutrition Assistance Program, or SNAP.
Reid has made it clear that an extension of the current farm law, passed in 2008, is unlikely as he presses the House to pass the Senate version of the bill. That leaves Boehner to figure out the next step before the current policy expires Sept. 30.
Congress also must figure out what to do about interest rates on college student loans, which doubled from 3.4 percent last Monday because of partisan wrangling in the Senate.
Lawmakers promised to restore lower rates when they return this week, both retroactively and before students start signing loan documents later this summer. For now, the rate stands at 6.8 percent, which is higher than most loans available from private lenders.
Congress faces political and economic fights over the budget, with the fiscal year ending Sept. 30 and Congress plodding through spending bills with no sign they will be done on time. The House is set to vote this week on the spending bill for the Energy Department.
In addition to legislation to keep the government running, Congress probably will have to vote on whether to raise the nation's borrowing authority, a politically fraught vote that roiled the markets in August 2009.
Three Senate committees will consider Obama nominees for major national security positions this month, confirmation hearings certain to set off a political dust-up over the president's policies though the criticism is unlikely to scuttle the selections.
Questions about the administration's policy toward Syria and plans to arm the rebels in their civil war with President Bashar Assad's forces will dominate the Senate Armed Services Committee hearing on the re-nomination of Gen. Martin Dempsey for chairman of the Joint Chiefs of Staff.
The hearing is scheduled for July 18.
The Senate Foreign Relations Committee is expected to hold a hearing on Samantha Power, the president's pick for U.S. ambassador to the United Nations, and a subcommittee meets July 11 to consider the nomination of Victoria Nuland for assistant secretary of state for European and Eurasian Affairs.
That posting typically wouldn't draw a great deal of attention, but senators are certain to press Nuland about her work on the widely debunked talking points about the deadly assault on the U.S. diplomatic mission in Benghazi, Libya. Four Americans, including U.S. Ambassador Chris Stevens, were killed in the Sept. 11 attack last year.
Susan Rice, the U.S. ambassador to the United Nations at that time, used the talking points five days after the attack, blaming the assault on a spontaneous protest over an anti-Islamic video.
The Senate Judiciary Committee holds a confirmation hearing Tuesday on Obama's choice of James Comey to serve as FBI director. If confirmed by the Senate, Comey, a top Bush administration lawyer best known for defiantly refusing to go along with White House demands on warrantless wiretapping nearly a decade ago, would replace Robert Mueller.
The administration's recently disclosed surveillance programs are likely topics for Comey's hearing.