HAS Gov. Mitt Romney become more conservative in the past few years or has he shrewdly tacked to the right to get the Republican presidential nomination?

We don't know. What we do know is that Romney's record involves more than just switching from a few liberal positions to a few conservative ones. It represents wholesale conversions on issue after issue, sometimes back and forth, and with some false biographical statements thrown in.

Any candidate for office is allowed to change his mind. People learn new facts or have personal experiences that bring them to new understandings. Not every switch is an opportunistic flip-flop.

The reason Mitt Romney has drawn our scrutiny on this issue, and we are not alone, is not because he is the only candidate who has changed positions. He is not. It is because the totality of his record gives the distinct impression that most of his positions are subject to change when politically expedient.

Whenever Mitt Romney has run for office, his public positions on the issues of the day have been in general agreement with the voter base whose approval he was seeking.

In Massachusetts he was pro-choice, then pro-life, then pro-choice, then pro-life again. He was even more pro-gay rights than Ted Kennedy, for strict gun-control laws, for affirmative action, against the Boy Scouts' policy on homosexual scoutmasters, for what he now calls "amnesty" for illegal immigrants, and against the Bush tax cuts.

How can he have changed his mind on all of those issues and others so soon after deciding to run for the Republican presidential nomination?

In addition to his rightward shift, Gov. Romney's record includes some personal statements that make him appear less than completely candid about who he is and what he believes.

He claimed to have been a lifelong hunter. He wasn't. He claimed to have had the NRA's endorsement. He didn't. He claimed to have marched with Martin Luther King Jr. He didn't. These cannot be explained away as conversions.

We have found Romney's enthusiasm for conservative princples to be situational at best. And we are not alone. We have listened carefully to Republicans who knew Gov. Romney during his political rise in Massachusetts. They do not believe he is a far-left liberal. But they don't believe he's as conservative as he now claims, either.

At the end of the day, Republicans have to pick one candidate for President. Some judge Mitt Romney to be truly conservative. We do not. We think his record shows that while he is a Republican, he is not as conservative as Sen. John McCain.

Those who know him have told us that at his core, Gov. Romney is a decent man. We believe that. We just don't believe he is a man of solid political conviction. That is what most Republicans want, in a President. And that is why we picked John McCain over Mitt Romney.