On the issues, not very much separates the front-runners for the Democratic nomination. What's interesting is that all of them -- Hillary Clinton, Barack Obama and John Edwards -- are running well to the left of the only Democratic presidents in the last 40 years, Bill Clinton and Jimmy Carter. The top Republican candidates, on the other hand, are all over the place on issues.

Mike Huckabee, leading in every December Iowa poll and No. 1 nationally in the Rasmussen poll, denounces "the Bush administration's arrogant bunker mentality" in the current Foreign Affairs and says that after Iran was included in the Axis of Evil in 2002, "everything went downhill fast." But the mullahs have been launching attacks on America since 1979. He sounds like almost as much of a populist as Edwards.

Huckabee's engaging personality and his status as a "Christian leader" (a caption in one of his ads) have propelled him ahead in Iowa. But Republicans should understand that his nomination would move the party left on foreign and economic issues. He's more like William Jennings Bryan than like Ronald Reagan.

Rudy Giuliani is closer to Bryan's contemporary Theodore Roosevelt. They both experienced running for mayor of New York and losing. (Roosevelt in 1886, Giuliani in 1989). Giuliani calls for taking the offensive on foreign policy and on domestic policy stresses reforms like school choice. He is at odds with most Republicans on some cultural issues. But more damaging to him is his personal life, which has been messier than that of any Republican president.

John McCain is an admirer of Roosevelt and, like him, has fought party regulars on some fronts -- campaign finance, climate change and the Bush tax cuts (though he now favors extending them). He also stands for a vigorous foreign policy and has advocated a surge in Iraq since 2003. McCain's abhorrence of pork and earmarks means his administration might engage in bitter brawls with bipartisan pork lovers in Congress.

The other two leading candidates, Mitt Romney and Fred Thompson, stand closer to traditional Republican views. But Romney got to that place on some issues very late in the game. He's also had to talk more recently about his Mormon faith, which for some voters puts him beyond the pale. He's talked less about his strength as a manager, setting up businesses and rescuing the 2002 Winter Olympics.

Thompson, who led in Rasmussen's national polls last summer, before he officially announced, is the closest to the Republican mold, though not on campaign finance and trial-lawyer issues.

You can write three or four scenarios for how the Democratic race will go; you can write 60 for the Republicans. But there are a couple of things to keep in mind as Republicans decide. One is that it seems increasingly possible that no candidate will emerge from the primaries and caucuses with a majority of delegates. That uncertainty means the nominee may not be determined until late spring. Such tardiness could help Democrats in a year when voters already say they'd prefer a Democratic president to a Republican.

Second, the preference for smaller rather than larger government is not as ample as it used to be. The strongest case against big government has been its failures in the 1970s, typified by gas lines and stagflation. But the median-age voter in 2008 was born around 1964, so he or she never sat in those gas lines or struggled to pay rising bills with a paycheck eroded by inflation. That demographic factor helps explain why Democrats today are promising big-government programs, unlike Bill Clinton in 1992, when the median-age voter remembered the 1970s very well.

America has enjoyed low-inflation economic growth for 95 percent of the 2008 median-age voter's adult life. This is a record unique in history, which neither party is addressing particularly well. Democrats promise tax increases on at least some high earners (by not extending the Bush tax cuts past 2010), though tax increases are not the usual prescription for an economy that may be headed toward recession.

Republicans, facing an electorate half of which doesn't remember the 1970s and most of which has not appreciated the generally good economy we've had since 2001, have yet to muster persuasive arguments for their policies.