The Arizona and New York Senate races officially began Monday morning, with the appointment of two of the most powerful women in American politics to President-elect Barack Obama’s Cabinet.

The respective nominations of Sen. Hillary Rodham Clinton (D-N.Y.) and Arizona Gov. Janet Napolitano (D) as secretaries of State and Homeland Security essentially free up the Democratic nominations for those states' Senate races in 2010.

In both cases, the appointments appear to be electoral negatives for Democrats, who will now have to defend an open seat and find a viable opponent for McCain.

With much jockeying already taking place in Illinois for Obama’s vacated seat, the sweepstakes in New York should easily rival it now that Clinton’s nomination is official.

Gov. David Paterson (D) must choose an appointee from a diverse field including a potential primary opponent to himself in the 2010 governor’s race, more than 20 Democratic House members and even a couple members of the Kennedy family. He has said he will not appoint himself.

Attorney General Andrew Cuomo (D) is the consensus strongest  pick for the post, not least because he is thought to be a strong opponent for Paterson in two years. Paterson ascended to the seat earlier this year after a prostitution scandal forced Gov. Eliot Spitzer (D) out.

Also thought to be near the top of the list are Democratic Reps. Nydia Velazquez, Kirsten Gillibrand, Brian Higgins, Nita Lowey, Gregory Meeks and Steve Israel, along with Buffalo Mayor Byron Brown and Nassau County Executive Tom Suozzi.

Environmental activist Robert F. Kennedy Jr. and his cousin, Caroline Kennedy, also are being mentioned.

Paterson faces a difficult balancing act in a state with many powerful Democratic sects and an executive branch dominated by white men from New York City.

Gillibrand, Higgins and Brown could help mollify up-staters hoping for one of their own; Velazquez or Bronx Borough President Adolfo Carrion Jr. would give Hispanics a senator; and Meeks would be the only African-American in the Senate, pending a potential black successor to Obama.

A Marist College poll from two weeks ago showed 43 percent of New Yorkers wanted Cuomo as the appointee, though that could be in large part because his name recognition far outpaces members of the state’s House delegation, who were relegated to single digits.

Whoever is appointed will have to run for the seat in 2010 and again for a full term in 2012, making the appointee’s ability to campaign a key criterion.

Depending on the pick, he or she could be in for a primary challenge and a match-up with former New York Mayor Rudy Giuliani (R) in 2010. Giuliani is also thought to be a potential candidate for governor.

Upwardly mobile Democrats could feel pressure to challenge the appointee in a primary in two years, especially if he or she is relatively young. The state’s other Senate seat appears locked up for years to come with 58-year-old Sen. Charles Schumer (D) comfortable, and having another Democrat monopolize the other seat could severely reduce opportunities for federal promotions in the years to come.

While New York will heat up, Arizona might cool off.

McCain has seen his popularity wane in the state in recent years as Democrats have made demographic and electoral gains, and he actually trailed Napolitano in some hypothetical match-ups for 2010.

Napolitano was also term-limited, so the Senate race appeared a logical choice.

Her exit leaves less attractive but potentially viable options, including Rep. Gabrielle Giffords and state Attorney General Terry Goddard.

Though Democrats now control five of eight House seats in the state, Republicans maintain both Senate seats and have now ascended to the governorship, with Republican Secretary of State Jan Brewer moving to the governor’s mansion to replace Napolitano.

In an e-mail to supporters within minutes of her appointment, Napolitano alluded to the position in which her move leaves state Democrats for the coming cycle.

“We reached another milestone by electing four more Democrats to Congress (in the last six years, and) sending a majority to Washington this January,” Napolitano said. “And we've built a Democratic Party that's stronger, smarter and better positioned for victory in 2010 than ever before.”