Don’t assume that the first flurry of polls we’ve seen this week will reflect the 2008 electoral landscape two or three weeks from now. Like the Democratic convention bounce that benefited Sen. Barack Obama (Ill.), the Republican bounce that now benefits Sen. John McCain (Ariz.) is likely to dissipate.

[IMGCAP(1)]Where the race will be a month from now depends not only on what happens during the daily campaign war, but also on whether the most recent CNN/Opinion Research survey is a mirage or an accurate indicator of a fundamental change that has occurred in public opinion.

The CNN survey, and to a lesser extent some of the other recent surveys, suggest an electorate that is hardening along traditional lines, with half the country preferring change, Democrats and Obama, and half opting for strength and experience, Republicans and McCain.

If that’s true, it suggests a return to the partisan equilibrium that we saw in 2000 and 2004, and a tight race all the way to November. Given the strong mood for change and the sense of impending doom in Republican ranks just a few weeks ago, that would be disappointing news for Democratic partisans who hoped to avoid a nail-biter.

The most recent CNN/Opinion Research poll found a dramatic rebound by the Republican Party. If that has occurred — and it still is nothing more than an “if” — then it changes the entire dynamic of the election.

The survey showed a significant drop in the public’s view of the Democratic Party — from 56 percent favorable/35 percent unfavorable in late April to 51 percent favorable/40 percent unfavorable now — and a corresponding improvement in the GOP’s image, from 38 percent favorable/53 percent unfavorable in April to 48 percent favorable/45 percent unfavorable now. That still leaves the Democratic Party with a better image, but the difference between the parties’ standings is far less dramatic than it was.

It also showed what can only be described as the total collapse of the party’s advantage in the “generic Congressional ballot” question, which asks respondents whether they plan to vote for the Republican or the Democratic candidate for Congress.

The Sept. 5-7 CNN poll showed Democrats with a 3-point advantage on the generic ballot, 49 percent to 46 percent. In November, the Democrats held an 11-point advantage (53 percent to 42 percent), and in June of 2007, their advantage was a dozen points (53 percent to 41 percent).

Most surveys have shown the Democratic Congressional generic ballot advantage to be 8 points to 15 points for more than a year, so a dramatic narrowing of those numbers would be significant. I’m not yet ready to believe that has happened until I see corroborating data.

For months, I’ve argued that the public’s disconnect between McCain’s brand and the GOP brand was filled with both risk and opportunity for Republicans. Either the party’s terrible image could rebrand McCain, causing him to plummet in the polls and dragging him down to defeat, or McCain could redefine the Republican Party and improve its image.

While the CNN poll suggests that McCain’s image — or running mate Sarah Palin’s — has re-branded his party, it is far too early to conclude that that is exactly what has happened. The recently released NBC News/Wall Street Journal survey, which rarely jumps around erratically and therefore has earned my admiration, showed less redefinition of the parties.

That survey found Republicans now with a 40 percent positive/43 percent negative image, compared with a 27 percent positive/48 percent negative image in April. The obvious explanation is that rank-and-file Republican partisans are now feeling better about their party and have responded that way to pollsters. Unlike the CNN survey, the NBC News/Wall Street Journal poll showed the Democrats’ image essentially unchanged from the spring, and that they have a far better reputation than the GOP.

Unfortunately, none of the NBC News/ Wall Street Journal, the USA Today/Gallup or the ABC News/Washington Post poll included questions about the generic Congressional ballot.

Whether or not the Republican Party’s image has improved is no small matter.

McCain has been forced to swim against a strong current, and his task would be made easier if voters had a significantly more positive view of the GOP. Just as importantly, a much closer generic Congressional ballot, especially combined with a more positive image for the Republican Party, would improve GOP prospects in upcoming House and Senate elections, reshaping a landscape where some Republican incumbents are at risk primarily because of their partisan label.

Republicans, quite naturally, will prefer to believe the CNN numbers. But unless and until other surveys confirm a new political reality in the electorate, it’s wise to be cautious and assume that Republicans are still swimming against a strong tide.

Stuart Rothenberg is editor of the Rothenberg Political Report.