(NOTE FROM JOHN: Tom Wellington (a pseudonym) is a longtime Democratic campaign operative, and is our newest blogger at AMERICAblog. This is a follow-on to his earlier post titled “The one who primaries Obama will be the next Democratic president.”)

Researchers in the 1950s found that children who had nightlights in their rooms tended to have bad night vision when they grew up. So for decades standard parenting advices warned against purchasing your children nightlights. But then upon reexamination, they discovered that parents who had bad night vision had trouble seeing when they got up in the middle of the night to check on their children – so they bought nightlights. And of course, parents with bad eyes tend to have children with bad eyes.

Two clocks strike midnight ten seconds apart every day – the first does not cause the second.

An incumbent who has so angered his base that he is primaried would be in trouble in a general election, regardless of whether or not he faced a primary challenge. So yes, Jimmy Carter was primaried and lost the general election, and the same happened to Jerry Ford. But does anyone think that, even without a primary, Carter would have beaten Reagan, or that Ford could have been elected after pardoning Nixon? Or even that George Bush Sr. could have beaten Clinton if only Bush had not been challenged by Buchanan?

Primary challenges are a different animal than third party candidates. Third party candidates can and do act as spoilers, taking votes away from what would otherwise have been a lesser of two evils. So although there were plenty of other reasons Al Gore lost in 2000, had Ralph Nader not been on the ballot, Gore would have won. That is a provable mathematical fact.

The “primarying Obama will get us President Bachmann” argument is the same type of fear tactic the Republicans are playing with the debt ceiling. Threaten the apocalypse, then settle for complete surrender. We are not going to have President Bachmann. The policies the Republicans are pushing are anathema to average Americans, and polling proves that. Regardless of whether Obama is the nominee, we will win if we can make a clear contrast to the voters. In fact, we would be better able to make that contrast with a different nominee.

Primarying Obama will be good for the Party and the eventual nominee

Without a primary challenge, the news cycle for the next fifteen months will be about Republican candidates tearing down Democrats in Congress and the White House. Given the President’s above-it-all approach to anything even slightly partisan, expect no effective response. But imagine a primary challenger out there 24/7 attacking the Republicans and putting forward a coherent progressive vision. In the 2004 election, while Kerry, Dean, Edwards and the others were publicly bashing Bush, his ratings went into a free fall. Bush only recovered when Kerry locked up the nomination and disappeared from public consciousness until the convention – by which time it was too late.

Primaries build organizations and parties. Had Obama won in New Hampshire and eliminated Clinton, and all the others, with the first primary he would never have built the nationwide grassroots organization that propelled him to victory. He had to campaign in states that Democrats had written off in the general for years, and found surprising strength – with the result that Democrats put resources into places like North Carolina and Indiana and turned them blue. It was also a time when Obama found some of the problems in his message, and tried to fix them.

I worry that this time around the President’s campaign advisors are assuming a level of grassroots activism that is not in fact there. If that is true, we are much better off if we discover it now.

But the most important result of this primary challenge will be the building of a nationwide progressive grassroots movement that will continue on after 2012 regardless of the outcome. If that movement does not nominate its choice in 2012, so be it. But consider what 2013 would look like if Obama were not primaried and lost anyway — we would not have built the infrastructure we’d need to oppose the ruling tea party conservatives. And in 2016, the Democrat who challenges (and perhaps loses to) Obama in 2012 will start out as the prohibitive favorite.

Don’t forget that the conservative movement we are fighting today came together out of Ronald Reagan’s primary challenge, and loss, to Gerald Ford in 1976. In retrospect, it’s difficult to call Reagan’s move anything less than brilliant for himself and his party.