It's a measure of how little loyalty Romney commands within his own party that so many are publicly calling on him to release his tax returns.
As Mitt Romney continues to insist he's not going to release more than two years of tax returns, he's getting strikingly little backup from his own party. Here is a list of some prominent Republicans who have so far urged him to release more tax returns:
Even as the nominee, Romney inspires remarkably little loyalty within his own party -- perhaps a consequence of the ugly fashion in which he won the primary, or perhaps because he is clearly at best a poorly assimilated immigrant to the GOP's right wing. As Dave Weigel points out, you didn't have a chorus of Democrats in 2008 calling on Barack Obama to release his birth certificate or college transcripts. But Romney doesn't have the stature, or the power, to make Republicans fall in line.
Not having seen the tax returns, these Republicans are hardly in a position to weigh the benefits of releasing them against the potential costs -- such as the political damage to Romney if it turns out he managed to legally avoid paying any taxes at all, as the Obama campaign is now speculating in a television ad. If that or something like it is the case, it's unlikely that Romney could easily "put this thing to rest" as so many are now urging; instead, it would be the contents of the returns, rather than their disclosure, that became an endlessly litigated issue. (John McCain, who saw 23 years' worth of Romney's tax returns when he was being vetted for the vice presidential nomination in 2008, vouched Tuesday that there was "nothing disqualifying" therein, though it has been suggested that 2009 is the most potentially damaging tax year for Romney.)
But either the dissenting Republicans don't feel they owe Romney anything, or they think they're doing him a favor by giving him good advice. In the latter case, it's revealing that they they don't have confidence in the Romney campaign's ability to make the right decision on its own. But The Hill's Niall Stanage pointed me to another important possibility: As a matter of ideology, these Republicans want Romney to stop acting ashamed of his wealth. Instead of worrying that people won't like the truth about his money, they wish he would put it all out there and own it.