To sustain the country’s unified spirit during its goodbye to Ronald Reagan, why don’t President Bush and Democratic Sen. John Kerry (Mass.) resolve to campaign with positive messages?

Reagan was a popular president, but I think that at least part of the outpouring of affection we saw for him last week resulted from the public’s desire to be unified for awhile amid one of the nastiest presidential campaigns ever. [IMGCAP(1)]

Instead of flinging epithets at each other and “defining” their opponent down, the candidates might start a debate about real issues like health care, the economy or foreign policy.

It’s true, both Bush and Kerry do deliver speeches on such serious subjects — and they will do so again this week — but they rarely talk back to each other about the same subject, and the press rarely forces them to engage in debate.

In paid advertising, the Bush campaign has spent most of its money accusing Kerry of being a tax-raising, weak-on-defense flip-flopper. It’s only just occurred to the Bush team that the public still doesn’t appreciate that the economy is surging. So the latest round of Bush ads — unfortunately for the president, unveiled during the week of Reagan’s state funeral — tout job growth. Bush ought to keep that up.

The Bush team also is sending out teams of surrogates to make speeches and TV appearances twice a month, when new national job figures are released and when state-by-state numbers come out.

In the meantime, the public is also largely unaware of good things happening in Iraq. Bush could do worse than to run ads quoting Iraq’s new prime minister and president praising the United States for the sacrifices that have made their country free.

What tends to dominate the news — and thus the public’s awareness of the campaign — is bad news from Iraq combined with a constant barrage of negative attacks.

Continuing my self-appointed role as campaign dirt detector — or low-blow score-keeper — it remains true that Democratic blasts at Bush are far harsher than those headed in the other direction.

For instance, former Vice President Al Gore said in one of his MoveOn.org diatribes that President Bush has “betrayed the country.” Abu Ghraib, Gore said, is “a Bush gulag.”

Granted, Gore is not a Kerry spokesman, but neither has he been rebuked by the candidate for going over the top. Meantime, Kerry’s wife, Teresa Heinz Kerry, accused Bush of being “unpatriotic” for questioning the candidate’s record on national security. No Republican has used the “u” word on Kerry yet.

The Bush tactic, rather, is to exaggerate flaws in Kerry’s record, claiming that he favors a 50-cent a gallon increase in gasoline taxes (he once did, but doesn’t now), that he wants to raise taxes on everyone to the tune of $900 billion (he favors increases for the rich worth $250 billion), and that he opposes anti-terrorist wiretaps (he doesn’t).

On May 31, The Washington Post detailed the Bush team’s exaggerations in a story headlined “From Bush: Unprecedented Negativity.” The Bush campaign issued a lengthy rebuttal of the story, citing Kerry votes and statements to justify its charges. In most cases, it seems to me that the Bush camp has stretched the evidence to undercut Kerry.

The worst part of the Post story, though, was that it mentioned only in one buried sentence the fact that Kerry’s personal attacks on Bush have been far harsher than Bush’s. (Note to readers: I invite help in keeping track of campaign dirty pool. I’m at mmk@rollcall.com.)

Another argument for the candidates’ waging a positive campaign is that negativity hasn’t moved many voters. Bad news from Iraq has overwhelmed good news about the economy. The result has been to depress Bush’s approval ratings and help Kerry.

A Los Angeles Times poll last week gave Kerry a 7-point lead nationally in a two-man matchup — 51 percent to 44 percent — and a 6-point lead, 48-42, in a three-way race with Ralph Nader, who got 4 percent. (Republicans claimed that the poll had overrepresented Democrats.)

A June 8 Gallup Poll had Kerry up, 50 percent to 44 percent, in a two-way match among likely voters. The same poll found Kerry up, 49 percent to 43 percent, when Nader is included, winning 5 percent. Bush’s overall job approval in the poll was 49 percent, although on Iraq and the economy it was 41 percent.

A Fox News/Opinion Dynamics poll released June 10 showed Bush and Kerry tied at 42 percent in a three-way race, with Nader at 3 percent and 12 percent undecided. Bush’s approval was at 48 percent.

In the meantime, “red” states — those carried by Bush in 2000 — gave Bush a lead of 48 percent to 39 percent in the Fox poll. In “Blue” states carried by Gore, Kerry led by 44 percent to 38 percent. And in 15 “battleground” states, Kerry led by 43 percent to 40 percent.

The polls certainly argue for Bush to quit spending his ad money to criticize Kerry and to instead start telling the country what’s right with Iraq and the economy — and, for that matter, what Bush might do in a second term.

Kerry’s ads, mostly about his own biography, have been generally positive. Recently, he’s been riding a wave of bad news for Bush that may not last, so it behooves him to start saying what his program is for the future.

Now is a good moment to start. Reagan was a successful president, close to being a great one. Bush and Kerry ought to vie to convince voters that they can fill his shoes.