The Senate has approved an ambitious immigration reform bill that would expand the guest-worker program to admit 200,000 more immigrants each year to do "jobs Americans won't do." It also charts a route to citizenship for a major portion of the 12 million immigrants illegally residing north of the Rio Grande and increases sanctions for employers who make unlawful hires.
The House is poised to eviscerate this legislation by replacing major provisions with its own "law and order" version. This approach emphasizes a crackdown on unlawful workers, levies harsher penalties on businesses that violate the law and rejects additional guest workers.
Most Congress watchers believe the upshot will be a stalemate followed by more deadlock and drift on immigration policy.
Why has the Senate approved by an overwhelming margin an immigration bill that seems doomed in its sister chamber?
The answer lies in the politics of the two bodies.
Only one-third of the 100 senators must stand for re-election in November. It just so happens that the vast majority of those on the ballot appear to hold safe seats, which gives them more leeway. Among the exceptions are Democrat Ben Nelson of Nebraska and Republicans Rick Santorum of Pennsylvania and Lincoln Chafee of Rhode Island.
In addition, at least 14 senators are flirting with a run for the White House in 2008, and all except Virginia's George Allen, a Republican, sought to propitiate the Latino community by supporting the Senate's immigration initiative.
Hispanic voters play a greater role in presidential contests than in so-called off-year elections because they are concentrated in states that abound with Electoral College clout. Further, greater media fanfare means that far more lower-income citizens, including recent immigrants from Latin America, participate in presidential balloting.
While just 33 senators must face the electorate this year, all 435 House seats are up for grabs. As a rule, incumbents are shoo-ins for re-election because of fat war chests, greater name recognition than their challengers and district lines drawn to their advantage.
The outcome of this year's electoral ballgame is far less predictable. Americans are disgruntled with the federal bungling after Hurricane Katrina, the Iraqi quagmire, the soaring price of gasoline and the scandals that have erupted on Capitol Hill.
GOP legislators are also spooked by President Bush's low approval rating, which is only a handful of points above that of Richard M. Nixon on the eve of his resignation in August 1974. Unless the chief executive stages a comeback, he might cost the average Republican candidate many votes in the fall showdown.
Then there is the battle over the porous U.S. border with Mexico. The May 1 "Day Without Immigrants" protests appeared to have backfired, in part because some demonstrators hoisted Mexican flags even as the media reported on a Spanish rendition of "The Star-Spangled Banner."
In the aftermath of this event, a Zogby International survey found that 56 percent of respondents preferred the tougher House bill and only 28 percent backed the more lenient Senate plan. A recent NBC News/Wall Street Journal poll indicates that Hispanics, who overwhelmingly support the Senate deal, prefer Democrats in the congressional elections, 55 percent to 22 percent. Poll results are volatile, but legislators will err on the side of caution.
Thus, House Speaker Dennis Hastert has vowed not to bring an immigration bill to the floor unless a majority of the 231 Republican congressmen endorse its provisions.
The probable failure of Congress to craft legislation will further sour the American public on its elected officials while ensuring that immigration - virtually neglected two years ago - will become a central issue in the 2008 race for the Oval Office.
George W. Grayson teaches government at the College of William & Mary in Virginia. His e-mail is firstname.lastname@example.org.