AUSTIN, Tex. — For much of the last three months, the most popular Joseph R. Biden Jr. website has been a slick little piece of disinformation that is designed to look like the former vice president’s official campaign page, yet is most definitely not pro-Biden.

From top to bottom, the website, JoeBiden.info, breezily mocks the candidate in terms that would warm the heart of any Bernie Sanders supporter: There are GIFs of Mr. Biden touching women and girls, and blurbs about his less-than-liberal policy positions, including his opposition to court-ordered busing in the 1970s and his support for the Iraq war. Pull quotes highlight some of his more famous verbal gaffes, like his description of his future boss, Barack Obama, as “articulate and bright and clean.” The introductory text declares, “Uncle Joe is back and ready to take a hands-on approach to America’s problems!”

All the site says about its creator is buried in the fine print at the bottom of the page. The site, it says, is a political parody built and paid for “BY AN American citizen FOR American citizens,” and not the work of any campaign or political action committee.

There is indeed an American behind the website — that much is unambiguously true. But he is very much a political player, and a Republican one at that. His name is Patrick Mauldin, and he makes videos and other digital content for President Trump’s re-election campaign. Together with his brother Ryan, Mr. Mauldin also runs Vici Media Group, a Republican political consulting firm in Austin whose website opens with the line “We Kick” followed by the image of a donkey — the Democratic Party symbol often known by another, three-letter, name.