TAMPA, Fla. --

, Ohio’s Republican U.S. Senate candidate and an outspoken critic of White House environmental policies, said Sunday that he doubts the presence of global warming.

The state treasurer thinks scientific research on the matter “is inconclusive and riddled with fraud.”

Mandel, who faces incumbent Democratic Sen. Sherrod Brown this fall, made the comment during an interview with The Plain Dealer here on the eve of the GOP convention. Mandel, of Beachwood, also addressed Ohio delegates at a brunch.

The convention, under threat of severe weather from Tropical Storm Isaac, will quickly gavel in and out of session Monday as a formality, recessing until 2 p.m. Tuesday. A revised schedule released Sunday shows Ohio Gov. John Kasich and Sen. Rob Portman of the Cincinnati area remain in choice evening speaking slots on Tuesday and Wednesday, respectively.

U.S. House Speaker John Boehner of West Chester will lead off Tuesday evening’s session. He had been scheduled to speak at the outset of Monday’s program.

The shortened calendar of festivities will conclude Thursday when former Massachusetts Gov. Mitt Romney officially accepts his party’s nomination for president.

Mandel planned to return to Ohio after his brief visit with the Ohio delegation.

Known for his reluctance to voice clear and specific thoughts on current issues, he sat for his most detailed policy discussion yet with the newspaper. Though Mandel remained vague in some areas, he went a step beyond his usual “war on coal” rhetoric.

Appearing with Romney this month at a southeastern Ohio coal mine, Mandel said those who worked to advance clean-air standards would do so “over our dead bodies.”

Pressed about the remark Sunday, Mandel said he was using a “colloquial” phrase.

“As a United States senator, I will do everything I can to block radical special interest groups . . . from killing energy jobs and manufacturing jobs in Ohio,” he said. “It is impossible to disconnect energy issues from manufacturing because Ohio manufacturing jobs depend on a skilled labor force, affordable energy and affordable raw materials.”

Though he often characterizes President Barack Obama and Brown as being in league with those “radical” groups, Mandel said he sees the need for environmental regulation.

“I believe we need regulation in this country to protect the air we breathe, the water we drink and the environment for our kids and grandkids,” he said. “My problem with the regulation coming out of Washington is I believe it’s gone beyond common sense and now it’s killing jobs in our state.”

Pressed further on his skepticism over widely accepted scientific reports of global warming, Mandel said: “I’ve never claimed to be a scientist, and I never will.”

But he referred to reports from Europe that his campaign spokesman, Travis Considine, later identified as from Fritz Vahrenholt, a German former environmental leader who has said that the role of carbon dioxide, emitted from coal, is overestimated.

Mandel also shared his thoughts on foreign trade. He said he believes China manipulates its currency and that Democrats led by Obama have not done enough to stop the practice, which accusers say weakens American manufacturers’ ability to compete.

Mandel indicated that he would not have supported a stalled bill to clarify the right to seek punitive duties if a country like China manipulated its currency.

“We must be vigilant in taking them on and making sure they play by the rules. At the same time, my approach would be a diplomatic approach, not a legislative approach.”

When reporters noted that diplomacy by President George W. Bush, a Republican, also failed to stop the practice, Mandel said he believed Romney would be aggressive with China on trade.

“I don’t think the Chinese have a lot of respect for President Obama,” Mandel said. “Consequently, I believe it’s difficult for President Obama to negotiate from a position of strength with the Chinese.”

On health care, Mandel reiterated his opposition to Obama’s Affordable Care Act, save for requirements to cover those with pre-existing medical conditions and to allow young adults to remain under their parents’ coverage up to age 26. But he believes “most of the rest of the bill is a job-killer,” and offered a few alternative plans he would support.

He talked most enthusiastically about fostering physician-owned hospitals as a way to create competitive, effective alternatives, and tort reform. And he slammed Obama for using hundreds of billions of dollars in Medicare cost-savings – Republicans call them cuts – to fund the health care program.

Mandel declined to endorse the Medicare changes proposed by Romney running mate Paul Ryan. As chairman of the House Budget Committee, Ryan has favored issuing vouchers to future Medicare recipients to buy private insurance. More recently Ryan has said the vouchers could be used to buy traditional Medicare if desired.

“While I respect him as a person and a leader, I am going to wait until I arrive in the Senate to work on a specific plan to save Medicare, because I think it has to be done in a bipartisan way, and we have no idea what the makeup of the Senate is going to be, come January,” Mandel said.

He added: “My grandmother is 83 years old. I think it’s unfair to change Medicare in any way for my grandmother’s generation. My parents are 59 and 60. They’re baby boomers. I think it is unfair to change Medicare in any way for my parents’ generation.

“But when you look at kids who are in elementary school and high school today, if we do nothing there will be no Medicare for them.”

Mandel also talked politics. On a day that a poll from the Columbus Dispatch showed the race between him and Brown a dead heat, he renewed a complaint that his opponent’s television commercials have been overwhelmingly negative in tone.

Outside groups on both sides have flooded the race with millions of dollars in attack ads, but Mandel asserts that his spots have been biographical and largely positive.

“Putting aside the outside groups, of the dollars that we can control, he’s chosen to use the dollars that he can control to run a vastly negative campaign, whereas I’ve chosen to use the dollars I can control to run a vastly positive campaign, and we believe that’s one of the main reasons we’ve gone from 17 points down to tied,” Mandel said.

Brown campaign spokesman Justin Barasky shot back late Sunday, noting Mandel’s history of making claims rated false by PolitiFact Ohio, The Plain Dealer’s fact-checking arm.

“It’s very easy to run positive ads when $15.2 million in outside money is being spent” by other groups who do the negative campaigning, Barasky said.

“He's not running a positive campaign. You can’t get six ‘Pants on Fire’ [ratings] from PolitiFact and run a positive campaign.”

With Plain Dealer Washington Bureau Chief Stephen Koff