BUDAPEST—Hungary appeared to backtrack on plans to build a Chinese university in the capital Budapest after thousands took to the streets at the weekend accusing the government of cosying up to Beijing, provoking an angry Chinese response. Opponents of Prime Minister Viktor Orban fear the planned private, $2 billion campus could undercut the quality of higher education and help Beijing increase its influence in Hungary and the European Union. A senior Orban aide said late on Sunday the university was not even at the planning phase, and once the plan took shape, in early 2023, it could be put to a referendum. “Once the project’s conditions are known, we support a referendum in Budapest to decide whether locals want Fudan University here,” Gergely Gulyas, Orban’s chief of staff, told the pro-government news web site Mandiner late on Sunday. Orban has built cordial ties with China, including massive joint business projects, …