WASHINGTON — Republicans preparing to pounce on Senator Obama’s running mate see his choice falling into one of two categories: “inexperience,” or an “insider.”

As Mr. Obama considers a vice presidential nominee for the Democratic ticket, he is eyeing candidates who would either underscore his message of bringing change to Washington or compensate for his perceived lack of national security seasoning or executive experience. Republicans, meanwhile, are preparing two parallel strategies to try to undercut Mr. Obama’s pick. If Mr. Obama picks a fellow fresh face, the Republicans will talk of the most inexperienced ticket in recent history. And if he picks an old Washington warhorse, Republicans will portray the selection as contradicting Mr. Obama’s call for an overhaul of Washington politics.

What follows is a rundown of how Republicans are preparing to portray four of the top vice presidential contenders, plus a wild card that could shake up the race:

TIMOTHY KAINE

The subject of intense speculation last week, Mr. Kaine, 50, is a first-term governor of Virginia whose selection by Mr. Obama would reinforce the message of change and bipartisanship. Despite modest approval ratings, Mr. Kaine is seen as popular in Virginia, a state that Democrats are targeting aggressively this fall. If he is selected, however, Republicans are sure to escalate their attacks on the Democratic pair as unprepared to lead the nation. “Obama-Kaine would be one of the most inexperienced tickets in American history,” a spokesman for the Republican National Committee, Alex Conant, said. Mr. Kaine has scant foreign policy experience and is barely more than midway through his first term as governor, having served as lieutenant governor and mayor of Richmond before that. Republicans in Virginia react with bemusement to the buzz surrounding him, saying he has accomplished little as governor and even less than his Democratic predecessor, Mark Warner, who had been the subject of vice presidential speculation before taking his name out of the running to focus on his bid for the Senate. “I don’t understand it,” the Republican majority leader of the Virginia House of Delegates, Morgan Griffith, said of the Kaine speculation. “Warner I would understand. Warner was successful.”

EVAN BAYH

Mr. Bayh, finishing his second term as a senator from Indiana, is universally seen as Mr. Obama’s “safe choice,” befitting the golden rule of vice presidential selection (borrowed from medicine): Do no harm. Republicans acknowledge that Mr. Bayh’s reputation as a moderate Democrat who is adept at staying on message and the absence of any hint of scandal make him one of the most difficult vice presidential choices to target. “There won’t be a lot of surprises that come with adding Evan Bayh to the ticket,” the co-chairman of the McCain campaign in Indiana, Luke Messer, said. The son of a longtime senator, Birch Bayh, Evan Bayh brings both executive experience as a former governor of the state and foreign policy chops as a member of the Armed Services Committee. What is missing from Mr. Bayh’s resume, Republicans will likely argue, is a single defining accomplishment, despite a long career that spans the Indiana Statehouse and Capitol Hill. “Truthfully, Evan Bayh is best recognized for being very cautious, not making mistakes, and having no real noted achievement,” Mr. Messer said.

KATHLEEN SEBELIUS

Mr. Obama would pick Ms. Sebelius, in her second term as governor of Kansas, to appeal to women voters and because of her success in getting elected and re-elected in a solidly red state. As with Mr. Kaine, the first word out of the Republican National Committee and the McCain campaign would be “inexperience,” with a focus on foreign policy. Democrats will portray Ms. Sebelius as a leader who has practiced the kind of post-partisan governing that Mr. Obama preaches. Republicans in Kansas say her bipartisan style comes solely out of necessity in a state where the Republicans controls more than 75% of the legislative seats. “She has worked with Republicans because, to get anything done in Kansas, you have to work with Republicans,” the executive director of the state Republican Party, Christian Morgan, said.

Ms. Sebelius has also drawn criticism in Kansas for her association with a doctor known for performing late-term abortions, Dr. George Tiller. Dr. Tiller is a campaign contributor to Ms. Sebelius, and the governor hosted a reception for him earlier this year. Their ties have already become fodder for conservative commentators and will likely be a bigger issue if she is named to the ticket.

JOSEPH BIDEN

The selection of Mr. Biden, a Delaware senator for 35 years and the chairman of the Foreign Relations Committee, would be aimed at reassuring voters concerned about Mr. Obama’s thin resume on international affairs. But Mr. Biden’s deep experience on Capitol Hill and his friendly relationship with many Republicans could also spin another way: He is a consummate Beltway insider, a reputation that brings gravitas but inherently conflicts with Mr. Obama’s call for a fundamental break with traditional Washington politics. Republicans will surely try to exploit that divide, and they are likely to characterize a Biden pick as a validation of their criticism of Mr. Obama’s lack of foreign policy experience. Mr. Biden is also known as gaffe-prone, and Republicans are likely to remind voters of as many of his verbal slips as they can. With Mr. Biden acting as a frequent surrogate for Mr. Obama on foreign policy, the Republicans have already dug up quotes from his unsuccessful primary campaign, when he questioned Mr. Obama’s experience and his rhetoric on foreign policy, particularly with regard to Pakistan.

CHARLES HAGEL

A Republican senator from Nebraska, Mr. Hagel is to Mr. Obama what Senator Lieberman is to Senator McCain, and his selection as a running mate would be an out-of-the-box choice that would create a headache for the Republicans. Mr. Hagel is a longtime friend of Mr. McCain’s and has yet to endorse Mr. Obama, but he supports the Democrat’s stance on foreign policy and has been cozying up to the Illinois senator of late. He also has shown no signs of bolting the Republican Party, forcing McCain supporters and surrogates to attack one of their own if he joins the ticket. One potential problem for Mr. Obama is that outside of foreign policy, Mr. Hagel remains a conservative. As one Republican strategist pointed out, his selection would undercut Mr. Obama’s attempt to tie Mr. McCain to President Bush because Mr. Hagel has voted with the president even more often than the presumptive Republican nominee.