Some issues, though, go to the core of each party's beliefs, giving voters a distinct choice. Abortion and taxes, both an important part of the primary campaign, are two.
Democrats talk of the need to keep abortion legal and ensure that women make their own healthcare choices, not "the government or ... some men sitting on the United States Supreme Court," as former Sen. John Edwards of North Carolina put it when Democrats held a debate in April. The major Republican candidates, with the notable exception of former New York Mayor Rudolph W. Giuliani, would like to reverse the high court decision legalizing abortion.
On taxes, all the leading Democrats would restore the higher rates paid by upper-income Americans before President Bush took office. In addition, Sen. Christopher J. Dodd of Connecticut has proposed a carbon tax to fight global warming.
Republicans, by contrast, emphasize spending cuts; some advocate lowering taxes even more. "I'd like middle-income Americans to be able to save their money and not have to pay any tax at all on interest, dividends or capital gains," former Massachusetts Gov. Mitt Romney said at the GOP debate last month in Simi Valley. (Former Sen. Fred D. Thompson of Tennessee, campaigning from the sidelines as he prepares to enter the Republican race, mainly echoes other top-tier candidates.)
The split over healthcare also reflects broad philosophical differences.
Generally, Democrats favor a bigger role for government in the nation's healthcare system, and Republicans advocate free-market steps toward covering the estimated 45 million people who lack insurance.
Edwards and Sen. Barack Obama (D-Ill.) would roll back the Bush tax cuts for upper-income Americans -- those making more than $200,000 a year under Edwards' plan and $250,000 a year under Obama's proposal -- to pay for expanded healthcare.
"I believe that unless we have a law requiring that every man, woman and child in America be covered, we're going to have millions of people who aren't covered," Edwards said at last week's New Hampshire debate. (Clinton, whose healthcare overhaul plan collapsed during her husband's presidency, has yet to unveil a comprehensive proposal.)
The leading Republicans reject that approach. Giuliani proposed giving Americans a tax deduction that would encourage them to buy whatever insurance they like, as they do for their homes or automobiles. "What the Democrats suggested on this stage two nights ago was socialized medicine," he said.
