Weekly Standard editor Bill Kristol said Monday that he thinks Mitt Romney should pay a higher tax rate, calling the rate he pays on his investments "weird."

"I personally -- if I were designing the tax code -- would have a tax code in which Mitt Romney paid more than 13 percent, given what I know about the kind of investments he made money from," Kristol said Monday on C-Span.

The prominent conservative commentator added that he thought there would be no "economic detriment" to Romney if he paid more.

"I think it just seems kinda weird that he pays a lower rate than an awful lot of middle-class people," Kristol said.

Romney released his 2010 tax return in January after intense pressure, showing that he paid a 13.9 percent effective rate on $42.5 million in income. His tax rate, lower than that paid by most middle-class filers, was because most of his income came from investments. Romney adviser Ed Gillespie said the candidate would release his 2011 return by October 15. Romney has refused bipartisan calls to release more years' worth of tax returns.

Romney's tax plan would keep the current 15 percent rate on interest, dividends and capital gains, but eliminate such taxes entirely for filers with less than $200,000 in income. Under the plan authored by his running mate, Rep. Paul Ryan (R-Wis.), Romney would have paid an effective rate of just 0.82 percent in 2010, according to the Atlantic.

Kristol said on C-Span he would be in favor of tax reforms that "muted" the difference between capital gains and ordinary income and "especially" did away with the carried interest loophole.

He repeated his call for Romney to release more tax returns.

Also on HuffPost:

Loading Slideshow...
  • Ron Paul

    "Politically, I think that would help him," Paul said in a interview with <a href="http://www.politico.com/news/stories/0712/78599.html#ixzz20w7ycTBE" target="_hplink">Politico</a>. "In the scheme of things politically, you know, it looks like releasing tax returns is what the people want."

  • Richard Lugar

    "I have no idea on why he has restricted the number to this point," <a href="http://www.cbsnews.com/8301-18563_162-57474352/pressure-mounts-on-mitt-romney-to-release-more-tax-returns/?tag=socsh" target="_hplink">Lugar said</a>.

  • George Will

    "I don't know why... he didn't get all of this out and tidy up some of his offshore accounts and all the rest," Will said on ABC's "<a href="http://www.huffingtonpost.com/2012/07/15/george-will-mitt-romney-bain_n_1674513.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+HP%2FPolitics+(Politics+on+The+Huffington+Post)" target="_hplink">This Week</a>." "He's done nothing illegal, nothing unseemly, nothing improper, but lots that's impolitic."

  • Bill Kristol

    "He should release the tax returns tomorrow. It's crazy," Kristol said on "<a href="http://www.huffingtonpost.com/2012/07/15/mitt-romney-tax-returns_n_1674325.html" target="_hplink">Fox News Sunday</a>." "You gotta release six, eight, 10 years of back tax returns. Take the hit for a day or two."

  • Robert Bentley

    "I just believe in total transparency," Bentley told <a href="http://abcnews.go.com/blogs/politics/2012/07/gop-governor-calls-on-mitt-romney-to-release-additional-tax-returns-and-show-he-has-nothing-to-hide/" target="_hplink">ABC News</a>. "In fact, I was asked today that question -- do you think that Governor Romney should release his tax returns? And I said I do. I said, I release my tax returns. I may be the only public official in Alabama that does, but I release mine every year and I just believe that people should release their tax returns. And if you get them out and just get past that, it just makes it so much easier."

  • Haley Barbour

    When asked on "<a href="http://www.nationaljournal.com/2012-presidential-campaign/barbour-romney-should-release-more-tax-returns-20120710" target="_hplink">The Situation Room</a>" if Romney should release more returns, Barbour said, "I would. But should it be an issue in the campaign? I don't think it amounts to diddly."

  • Michael Steele

    "If there's nothing there, there's no 'there' there, don't create a there,'" Steele said on MSNBC.

  • David Frum

    "Tax returns the next problem. Releasing returns under pressure: more weakness, more pain," Frum <a href="https://twitter.com/davidfrum/status/224509505973661696" target="_hplink">tweeted</a>.