Maine Democrats will attend caucuses Sunday to help choose their party’s presidential candidate. They have several strong choices, and picking among them might be difficult. Here are three general criteria to make it easier: Which candidate best represents the values of the party; which inspires the public to take part in their government; which has the most experience with the issues the next president is likely to face? There are certainly other important standards – depth of knowledge, ability to work across the parties, character, humility, work ethic, etc., but the three encompass some of those and can stand as proxy for others.

Democrats will approve their platform at their next convention, but if it looks like the 2000 version, the party’s values will turn on fiscal discipline, retirement security, consumer protection, investing in technological advances, opening trade markets, increased support for working families and an education reform proposal that looks much like the president’s No Child Left Behind plan. All of the six candidates – Gen. Wesley Clark, Gov. Howard Dean, Sen. John Edwards, Sen. John Kerry, Rep. Dennis Kucinich, the Rev. Al Sharpton – know their party’s stands and differ in small degree, although those differences must seem substantial to the candidates and their followers. One notable exception is Rep. Kucinich, who says his first act in office will be to repeal the existing trade agreements, voted with the majority of Republicans in favor of a constitutional amendment against flag burning and is a recent convert to the general description of pro-choice on abortion.

On who most inspires his political base, the choice is simple. Gov. Dean was their first to campaign as if he could win in November, who didn’t tiptoe around the president’s popularity and whose energy was infectious with voters. It was also infectious with the other candidates – their speeches and their ideas were sharpened by the governor’s campaign, and they have benefited because of it. Sens. Kerry and Edwards especially grasped what Gov. Dean seemed to have known instinctively. Democrats can decide which is the more important: to walk in with the right message or to learn and adjust over time.

The experiences of the candidates vary widely, making comparisons difficult. Gov. Dean has balanced a budget in Vermont; Sens. Kerry and Edwards and Rep. Kucinich were part of the Congress that balanced a federal budget in Washington. Gen. Clark and Sen. Kerry have led troops when a bad outcome was much more serious than red ink. And Sen. Kerry can claim the most foreign-policy experience and could make the further argument that he would be most skilled at persuading a Republican Congress to work with his administration.

There’s a fourth question that Democrats can’t seem to stop talking about: Who would have the best chance of beating President Bush in November? The answer is that no one knows the answer because no one knows what is going to happen in Iraq next summer, where specifically the economy will be in six months or whether some unpardonable gaffe will emerge from the mouth of a candidate. Ruminations on who can beat the president is fine for talk shows and op-ed columns, but the task before Maine Democrats this weekend is to choose someone who can forcefully make the case that the party’s choice should be the nation’s choice and then serve well should he be elected.