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Hours after Democratic candidate and former Vice President Joe Biden released his plan to address climate change Tuesday, individuals and the media began to point out some questionable similarities between passages of the presidential frontrunner’s proposal, posted to his website, and materials from other organizations and websites. Biden’s plan has since been changed to reflect appropriate citations.

While the candidate, of course, is almost certainly not directly responsible for writing and posting this himself, it’s still an embarrassing screw-up for the campaign—particularly as Biden’s run has been somewhat plagued by the memory of plagiarism accusations from his 1988 presidential bid. At the time, then-Senator Biden was accused of plagiarizing a speech from a British politician, though Biden has always claimed the incident was an oversight.

The recent accusations were first pointed out on Twitter by Josh Nelson, co-director of “progressive” telecommunications company CREDO Mobile. “The paragraph in Joe Biden’s climate plan about carbon capture and sequestration,” Nelson writes, includes language that “is remarkably similar to items published previously by the Blue Green Alliance and the Carbon Capture Coalition”—organizations that work at the intersection of environmental policy and labor.

On the left, Joe Biden’s climate plan. Source: https://t.co/WHWvRK784s On the right, a letter the Blue Green Alliance sent to leadership of the Senate Environment and Public Works Committee in 2017. Source (page 96): https://t.co/YxP3R16ZIo pic.twitter.com/oJSFXW742z — Josh Nelson (@josh_nelson) June 4, 2019

Business Insider also reported another instance of alleged plagiarism in the climate plan. Here’s text from the original campaign proposal:

Biden’s goal is to make CCUS a widely available, cost-effective, and rapidly scalable solution to reduce carbon emissions to meet mid-century climate goals.

And here’s text, as Business Insider points out, from the “our work” section of the website for the Carbon Capture Coalition’s Center for Climate and Energy Solutions:

Its goal is to make carbon capture, use and storage (CCUS) a widely available, cost-effective, and rapidly scalable solution to reduce carbon emissions to meet mid-century climate goals.

The Daily Caller also noticed something familiar about a section from the Biden campaign about the disproportionate harms of climate change and pollution on communities of color. Here’s the Biden campaign again, the Daily Caller notes:

40% of the 567 federally recognized tribes in U.S. live in Alaska where the rapid pace of rising temperatures and melting sea ice and glaciers threaten the critical infrastructure and traditional livelihoods in the state.

Compare that with text from Climate.gov, a federal website:

Of the 567 federally recognized tribes in the United States, 40 percent (229 tribes) live in Alaska Native communities. The rapid pace of rising temperatures, melting sea ice and glaciers, and thawing permafrost in Alaska is having a significant negative impact on critical infrastructure and traditional livelihoods in the state.

The Biden campaign told Business Insider, “Several citations were inadvertently left out of the final version of the 22-page document. As soon as we were made aware of it, we updated to include the proper citations.” They have since been updated. When Mother Jones reached out for comment, the campaign said it had “nothing further to give.”