By Chris Cillizza
Washington Post Staff Writer
Sunday, February 20, 2011; 7:54 PM
The surprise retirement announcement of Democratic Sen. Jeff Bingaman (N.M.) late last week means that a trio of southwestern states will hold open-seat contests in 2012, firmly establishing the region as a central battleground.
Bingaman follows Republican Sens. Jon Kyl (Ariz.) and Kay Bailey Hutchison (Tex.) to the sidelines; those three departures will account for half of all retirements in the Senate to date.
The vacancies are already creating a down-ballot domino effect, with every member of the New Mexico House delegation being mentioned as a possible Senate candidate and Rep. Jeff Flake established as the GOP front-runner in Arizona's Senate race.
Combine that ballot volatility with the rapid population growth in the Southwest over the past decade - the three states will gain five congressional districts before the 2012 election - and the focus on immigration issues in each, and the centrality of the region to both parties' winning calculus in the House, Senate and presidential level becomes clear.
"By 2012, the increase in population, which trended heavily toward independents, will have a major influence on the Senate and House races," predicted Frank Costanzo, a Democratic consultant who has worked extensively in the region. "And that will translate into the presidential race."
Both national parties are expected to seriously contest the Senate races in New Mexico and Arizona - although the incumbent's party retains an edge in each.
While Bingaman probably would have been reelected rather easily, an open seat in the Land of Enchantment is a dicier political proposition for Democrats.
Reps. Ben Ray Lujan and Martin Heinrich, both Democrats, as well as Steve Pearce, a Republican, are looking at the race. Former lieutenant governor Diane Denish (D) and former congresswoman Heather Wilson (R) appear interested, too.
Arizona is a mirror image of New Mexico. Republicans have far more success statewide than Democrats, but there have been breakthroughs - most notably by Janet Napolitano, who was elected to two terms as governor before leaving to head the Department of Homeland Security. (Napolitano has ruled out a Senate run.)
Republicans are trying to rally behind Flake, but his relatively moderate stance on immigration could draw a primary challenge - perhaps from the likes of controversial Maricopa County Sheriff Joe Arpaio.
Some in Democratic circles hold out hope that Rep. Gabrielle Giffords (Ariz.), who survived an assassination attempt last month, will recover in time to mount a statewide bid - a development that would fundamentally reshape the race and make it more likely that the party could pull off an upset.
Of the trio of southwestern states with open seat Senate races next year, Texas is the biggest stretch when it comes to competitiveness.
The last time a Democrat won a Senate race in the Lone Star State was in the late 1980s, and it's clear that the party's chances of breaking that ignominious streak lie almost entirely in an unelectable candidate emerging from what could be a crowded Republican primary.
For Democrats in Texas, however, 2012 may be only a building block. With Hispanics now comprising nearly four in every 10 residents and Republicans nationally still struggling to court Latino voters, the trend line in the state is a positive one for the party.
The booming Hispanic population presents a major challenge for Republicans not just in Texas but across the Southwest as the fight over how - and whether - to reform the country's immigration policies will be felt most deeply in the region.
With Hispanic populations rising across the country, how both parties fare in the southwestern Senate contests in 2012 will be a telling indication of their relative political health for some time to come.