US Senator Rand Paul has acknowledged that "mistakes" in his office had caused unattributed writing by others to appear in his own work and announced that he was instituting safeguards to prevent such breaches from happening again. While maintaining the defiance he has shown since the claims of plagiarism were first made last week, Paul hurriedly took steps on Tuesday to contain the biggest crisis of his young political career, one that threatens his ambitions to run for president in 2016. He said he was putting in place a more diligent system within his office to footnote and attribute material, part of what he called a restructuring on his staff. He said there would be no firings. Facing a cascading series of accusations that he used plagiarised material in speeches, an opinion article and a book, Paul said the lapses were the result of his newfound status as a freshman senator in high demand and the overwhelming workload it has brought for him and his staff. "What we are going to do from here forward … is we're going to do them like college papers," he said. "We're going to try to put out footnotes."