In 2006, McCain joined Democratic icon Sen. Edward Kennedy in sponsoring an immigration reform bill called "comprehensive" because it addressed all aspects of the issue. Its most controversial proposal would have provided a path to citizenship for nearly all illegal immigrants. In slightly different form, and with different sponsors, the proposal failed in 2007, amid a firestorm of public protest.

As McCain's campaign for the Republican presidential nomination faltered last summer, in large part because of his stand on immigration, he pulled back on his advocacy. Declaring that he "got the message" of public concern about ongoing flows of illegal immigration, McCain vowed he would "secure the border first." In addresses to Hispanic organizations, he has declared a firm commitment to the comprehensive approach. Still, he adds that such a bill can pass only after border security is assured.

Conclusion: Zig-zag but not a flip-flop.

McCain famously opposed President Bush's tax cuts in 2001, saying they would benefit wealthy taxpayers and could lead to too much red ink during a time of war. Many Republicans were angry at him for opposing President Bush. But McCain now advocates making the cuts permanent, arguing that the last thing the economy needs is higher taxes in an economic downturn. His critics call it a 180-degree switch.

Economic conditions are worse today, and Obama himself has a plan he says would lower taxes for low- and middle-income Americans. But critics might say that if tax cuts were ill advised in 2001, before the United States spent hundreds of billions on the Iraq war, they also should be a bad move today.

Conclusion: Flip-flop.

McCain has been a longtime opponent of subsidies for the grain-based fuel, and in the 2000 presidential campaign doubted its efficacy as a fuel source. He used ethanol to symbolically prove his anti-pandering, maverick bona fides. But in this campaign, he has been more favorable to ethanol, although he still opposes subsidies. He can be partially excused because when he ran in 2000, the cost of oil was far less than it is today. McCain also has evolved on global warming, saying it's better to err on the side of caution and pursue noncarbon-based fuels.

Conclusion: No flip-flop but a dollop of pandering.

PRESUMPTIVE DEMOCRAT NOMINEE

Obama long favored public financing of presidential campaigns and often portrayed his stand on public financing as one of principles aimed at keeping special interests at bay.

But after raising more than $200 million online with the most prolific small-donor support network in American political history, he reversed course and decided to privately finance his campaign, rejecting the $84 million in public financing McCain is preparing to take. McCain and campaign oversight groups were highly critical.

Obama said he was forced to forgo public financing because he was up against too many deep pockets from McCain, the Republican National Committee, and GOP-related groups. He also said his small-donor base itself was an antidote to big-money interests that often dominate campaigns.

But in reality, Obama and Democrats have more than kept pace with McCain and the Republicans so far, and this decision could allow Obama to outspend McCain in the fall. This was a strategic political decision.

Conclusion: Flip-flop.

Obama's critics hopped on a recent claim that he would "refine" his position on the war in Iraq after an upcoming trip there, his first in nearly three years, as a flip-flop. But in reality, Obama has been consistently in favor of a pullout of American troops throughout the campaign. He advocates a two-brigade-a-month pullout rate, which he says would get the U.S. out of Iraq sometime in mid-2011. His position on getting out has been consistent.

If Obama has been mistaken or waffled on anything related to the war, it was his predictions about what would happen with the "surge" of troops sent to Iraq last year and his reluctance to acknowledge that it has led to a greater degree of stability. In 2007, Obama predicted the surge would lead to a further "quagmire." But this month, his campaign quietly pulled down the surge criticism from Obama's Web site. Critics say he's been too rigid in sticking to a pullout plan that could undermine U.S. efforts to withdraw under a stable Iraqi regime.

Conclusion: No flip-flop but latent recognition of new reality.

Obama had earlier vowed to filibuster any legislation that gave retroactive immunity to telecommunications companies that cooperated with the government in potentially illegal wiretapping. The Bush administration says the legislation is important in the country's ability to intercept terrorists' communications.

But Obama recently voted for the FISA bill, causing a huge Internet backlash on his Web site and elsewhere, much of it from supporters who saw him as selling out to telecommunications companies. Obama said it was not an "easy call," that the new bill did worry him about potential abuse of executive privilege. And he vowed to retroactively try to strike problem passages. But he says the bill is an improvement over the one he opposed last year. Critics say he simply didn't want to look weak on terrorism in the middle of an election. But some critics of previous bills agreed with Obama that the new version had civil liberties safeguards the old one didn't.

Conclusion: Partial flip-flop.

GNS reporter Jerry Kammer contributed to this report.