I am not sure that is fair about centrism though. It may be true of the cautious political centrists, but centrist voters probably have more defined beliefs. But they are centrists beliefs.
For example - abortion.
Some people are anti-choice zealots. They are ready to kill or die to make abortion illegal. If you disagree and try to discuss it with them, they scream, call you names and thrust picturs of dead babies at you. That's one extreme side. Then other people are pro-choice zealots. They are ready to kill or die to make sure abortion stays legal. If you disagree and try to discuss it with them, they scream, call you names, and thrust pictures of back-alley abortions at you. A centrist is in between those two extremes. Not because they decided to just pick the middle ground but because they don't have a strong position on the issue and can see points on both sides.
I would argue that centrists pick the side that are more likely to get them votes and not try to get caught being extreme in their views to avoid losing votes. Not because they "spiritually" believe in the middle. AND, issues like abortion are issues that corporate America really doesn't have a stake in, other than using it as an issue to distract Americans from the issues that they care about and have a minority viewpoint on.
Another example - capitalism.
Some people are devoutly anti-capitalist. They hate capitalism and they hate corporations. Others are devoitly "free market". They love capitalism and hate regulations and taxes. Centrists are in the middle, seeing some problems with capitalism and some problems with regulation and trying to strike the best balance between socialism and laissez-faire.
Most of the time centrists AREN'T in the middle on this issue, but if you read between the lines on how they vote, they vote *FOR* free market ideologies and to reward their corporate backers. This is why the "centrists" are voting in the corporatist minority position on destroying health care reform, even though most of their constituents have the REAL "centrist" position that sides with the left on getting at least a public option, if not a single payer option available to Americans. They MASQUERADE that they care about middle America, but their voting record reveals otherwise. Kind of like how Liebermann votes first and campaigns heavily with Harkin to shut down the fillibuster a year or two ago, and now is the focal point of the filibuster against substantive health care reform, which he also has flipped flopped on to serve his corporate masters like a good so-called "centrist" does.
Real centrists, like Paul Hackett, who sided in the middle on things like gun ownership, but who was more populist on issues that set him against corporate interests get flushed out of the system pretty quickly, to avoid exposing the so-called "centrists" that are actually corporatists for what they are.
If Bayh really cared that "people in the middle" with certain "non-extreme" views are represented in Indiana by "centrist" Dems, and not Republicans, then why did he pull out a week before deadlines for getting on the Dem ballot are coming up, making it almost impossible for a Democrat to get his seat. Methinks he wants a corporatist Republican to win to help his buddies and solidify him a "Tauzin-style" job offering when he leaves, and screw over the party he never was really a part of.