One is politically safe and bipartisan - the Republican governor can mollify Democrats by selecting someone of either major political party who's seen as a caretaker, with little ambition for higher office.

The other is far more risky and pro-Republican, but has a potential upside for the GOP - he could choose a Republican who wants to run for the office in 2006 and be a viable statewide candidate for years to come.

The possible caretaker candidate mentioned most often is former Republican state Sen. Ross Johnson of Irvine.

If that happens, even Democratic lawmakers said Schwarzenegger would likely win relatively quick approval in the Democratic-controlled Legislature for the choice to replace outgoing Democrat Shelley, who announced his resignation Friday under a cloud of scandals. Senate President Pro Tem Don Perata, D-Oakland, has said he would guarantee safe passage for Johnson in the Senate.

Perata's predecessor, former Senate President Pro Tem John Burton, D-San Francisco, said it's an easy call.

"It's not a political test. It's a common-sense test," Burton said Saturday. "I do not believe a political choice would get through. Why would Democrats want to put a Republican into office who wants to run again?"

Burton said this might be the wrong time for Schwarzenegger to pick another fight with legislative Democrats when he's already at odds with them over his budget proposal and the so-called reform measures he's pushing.

"Why, when he's got all these beefs in the world, would he try to get into a beef over who he's going to appoint to this position?" Burton said.

But just because appointing an easily confirmed candidate is the path of least resistance doesn't mean that is the direction Schwarzenegger will go.

Schwarzenegger, who still enjoyed a 60 percent statewide approval rating in a recent poll, could take the more partisan and politically risky route - even if he knows the Democrats won't go along with it.

"If he names an up-and-comer, he can get credit within the party for trying to deepen its bench and brighten its future," said Jack Pitney, a government professor at Claremont McKenna College.

"He can reinforce the message that he cares about the Republican party, not just Arnold Schwarzenegger. It's always good for a governor to be seen as a team player."

The timing for such a move could be auspicious. Schwarzenegger is scheduled to address the state GOP convention Friday evening in Sacramento. He'll no doubt want to rally GOP support for his budget and the proposals he wants to see approved in a special election later this year.

Schwarzenegger can also apply pressure on Democrats in the Legislature by choosing someone with a reformer's reputation, added Pitney. One possible candidate for that role is Tom Campbell, Pitney said, a moderate Republican former legislator and congressman who Schwarzenegger recently chose to run his finance department.

"Schwarzenegger could argue that his nominee is a reformer," Pitney said, "and that legislators are just sticking to the old ways and rejecting reform. In the end, though, we could end up with a caretaker as a second choice.

"Democrats," he added, "don't have much incentive to advance an ambitious Republican. Conceivably if he picks someone with broad appeal, Democrats might feel some pressure to support that nominee but I don't know who that would be."

Other governors' experiences when facing similar decisions may be instructive to Schwarzenegger.

In 1988, then-Gov. George Deukmejian tapped Dan Lungren, a five-term Republican congressman from his hometown of Long Beach, to fill the vacancy left by the death of Democratic state Treasurer Jesse Unruh.

Lungren, seen as a young rising star in the Reagan era, confidently faced the Democratic-controlled Legislature. But while the Assembly confirmed the nomination, the Senate balked, subjecting Lungren to fierce questioning about his conservative voting record.

The upper house ultimately rejected the nomination when state Sen. Quentin Kopp, an independent, refused to support him.

Deukmejian followed up with a non-political choice, state Auditor General Thomas Hayes, who was easily confirmed. Hayes, a Republican, sought a full term as treasurer in 1990, but was soundly defeated by Democrat Kathleen Brown. Seventeen months passed between Unruh's death and Hayes' swearing in.

But in the process, the Democrats created a viable Republican statewide candidate out of a relatively anonymous congressman.

Lungren, his statewide stature raised by the confirmation battle, was elected attorney general in 1990, served two terms and was the GOP gubernatorial nominee in 1998.

In contrast, Gov. Gray Davis, a Democrat, took a more cautious, nonpolitical approach after Republican Insurance Commissioner Chuck Quackenbush resigned in disgrace in 2000.

McGeorge School of Law Professor Clark Kelso ran the Department of Insurance on an interim basis, and Davis appointed retired appellate court Justice Harry Low to serve the remainder of Quackenbush's term. Low never had any intention of seeking the office at the next election and was easily confirmed by the Legislature.

Sen. Dave Cox, R-Fair Oaks, who requested a state audit of Shelley's office last year that contributed to his downfall, said he would prefer that a Republican replace Shelley, though he believes Democrats won't support anyone who would pursue re-election in 2006.

"I'm a realist and recognize that my Democratic colleagues are probably not going to confirm a replacement who will stand for re-election just because the power of the incumbent is so great," Cox said.

In other words, anyone with ambition for higher office would set off a political firestorm inside the Capitol, where the partisan arguing has already been thick.

"I think it opens up the potential for another partisan fight," said Richard Temple, a Republican political consultant. "It's one more avenue for that to occur. The governor will have the appointment, and if the Democrats don't like it, they'll be fighting him over that, which doesn't help. Chances are there aren't a lot of people the governor and the legislative Democrats will agree is a good choice."

No matter what he decides, Schwarzenegger is in a position to win yet another potential skirmish with the Democrats, said Sherry Bebitch Jeffe, a University of Southern California political scientist.

"The way our governor is now going and the rhetoric he's now using, if he picks a strong candidate and the Democrats block it, it plays right into his hands. Even if he loses this one he wins. He can say, 'See, they're being partisan. The Democrats are playing to the special interests. I'm taking everything to the ballot.'

"The Democrats are the ones with the hard decision to make - whether to be perceived as obstructionists by opposing a strong nomination. His decision is easy. He can do either. That's why I figure he's going to pick the strong candidate."