A pair of columns published by Republican U.S. Rep. Mike Coffman of Aurora within the past year contain passages of previously published work by other House members but did not attribute the source of the information or writing.

The op-ed columns on different subjects were published beneath Coffman’s byline in The Denver Post and the Denver Business Journal.

The Post op-ed contains unattributed material from a budget proposal crafted by Republican U.S. Rep. Paul Ryan of Wisconsin, while the Business Journal op-ed contains material earlier published by U.S. Rep. Sam Graves of Missouri.

Ethics experts contacted by The Post said the duplicative writings fall short of their definition of plagiarism. But they said Coffman’s use of material by other writers failed to reach accepted standards for attribution.

Coffman is engaged in one of the most contentious congressional races in Colorado. The Post made its discovery of the duplicative writing when a Democratic operative associated with the campaign of Coffman’s rival, state Rep. Joe Miklosi, provided documents and alleged plagiarism to a reporter and the news organization’s editorial page.

Those documents were delivered to The Post on Monday — the day ballots were mailed to voters and a week before early voting begins.

After reviewing the documents, editorial-page editor Curtis Hubbard changed practices for future contributors meant to ensure that submissions are original work.

“There has always been an unspoken understanding that items submitted to the opinion pages are the original work of the author and that proper credit is given to other sources when it is due,” Hubbard said. “We have now spelled out that policy in writing and posted it to our website so there will be no question as to our guidelines moving forward.”

Coffman on Friday called the plagiarism allegations “absurd.”

“My staff are in constant collaboration with various committees, and a major role of committee staff is to help members create content,” Coffman said.

The Post’s editorial board operates separately from the newsroom, which conducted a review of the op-eds in question, along with recent op-eds published by Colorado’s current congressional delegation.

Staff for Coffman’s campaign said that in the unpaid Post op-ed April 15, House Budget Committee analyst Matt Hoffmann inserted an explanation that laid out the Republican majority’s plan to reform Medicare as part of its fiscal 2013 budget proposal.

Coffman’s campaign provided documents showing how the op-ed column was altered — at Coffman’s request — by Hoffmann, who inserted verbatim language from Ryan’s “Paths to Prosperity: A Blueprint for American Renewal,” published almost a month earlier.

Coffman said he didn’t know that the material came directly from the budget plan. Requests to Hoffmann seeking comment have not been returned.

Coffman’s campaign provided documents that detailed the collaboration that led to publication of the Business Journal op-ed Aug. 24.

In that instance, a Republican staffer for the House Committee on Small Business wrote an op-ed about the impact should the so-called “fiscal cliff” of tax increases next year transpire.

The staffer e-mailed Coffman’s staff, saying, “We’ve written for you to use as you wish.”

The Small Business Committee staffer also gave similar — but not exactly the same — material to other Republicans, including Graves, the committee’s chairman.

Coffman’s campaign said that collaboration with partisan staffers was common practice in Washington. And the campaign provided two instances in which significant portions of text were repeated in two pairs of op-eds published by Republican congressmen since 2009.

Coffman’s campaign also provided a copy of a Post op-ed by Denver U.S. Rep. Diana DeGette, a Democrat, that contained similar material to another source in a piece published earlier on the Rocky Mountain PBS website. DeGette’s duplicative wording amounted to three copied phrases — not full sentences or paragraphs.

Independently, The Post found one instance in which sentences in a Post op-ed written by DeGette later appeared in a press release by Democratic U.S. Rep. Jesse Jackson Jr.

Roy Peter Clark of the Poynter Institute observed the Coffman documents and said these kinds of events can occur when a politician or public official makes use of a ghostwriter.

“Responsible practice requires transparency: making it clear who wrote what,” Clark said in an e-mail.

Teresa Fishman, director of the International Center for Academic Integrity, said given the purpose and context of an op-ed, the original authors could easily have been noted.

“In my opinion putting forth text written by someone else as his own in an op-ed runs contrary to the legitimate expectations for an op-ed, i.e. that the content was produced by the person to whom it is attributed,” Fishman said via e-mail.

Staff researcher Vickie Makings contributed to this report.

Kurtis Lee: 303-954-1655, klee@denverpost.com or twitter.com/kurtisalee

Shared writing

A Denver Post op-ed by Rep. Mike Coffman uses the following language from Rep. Paul Ryan’s “Path to Prosperity” budget plan.

Identical content shown in italics.

From Rep. Coffman’s April 15 Denver Post op-ed:

“The second-least expensive approved plan or the traditional fee-for-service Medicare, whichever is least expensive, would establish the benchmark that determines the premium-support amount.

” If a senior chose a costlier plan than the benchmark plan, he would be responsible for paying the difference between the premium subsidy and the monthly premium. Conversely, if that senior chose a plan that cost less than the benchmark, he would be given a rebate for the difference. Payments to plans would be risk-adjusted and geographically rated. Private health plans would be required to cover at least the actuarial equivalent of the benefit package provided by traditional fee-for-service Medicare.”

From “The Path to Prosperity:”

“The second-least expensive approved plan or fee-for-service Medicare, whichever is least expensive, would establish the benchmark that determines the premium-support amount for the plan chosen by the senior.

If a senior chose a costlier plan than the benchmark plan, he or she would be responsible for paying the difference

Between the premium subsidy and the monthly premium. Conversely, if that senior chose a plan that cost less than

The benchmark, he or she would be given a rebate for the difference. Payments to plans would be risk-adjusted and

Geographically rated. Private health plans would be required to cover at least the actuarial equivalent of the benefit

package provided by fee-for-service Medicare.”

Note: In preceding paragraphs of Coffman’s op-ed, he references GOP House-passed fiscal year 2013 budget proposal.