BERLIN (AP) — The Green party candidate to succeed German Chancellor Angela Merkel has acknowledged making a mistake in a flap over allegations that she copied from others in a new book, saying that it would have been better to use a list of sources.

The claims that emerged last week have created severe turbulence for Annalena Baerbock's campaign, the latest in a series of troubles to hit the environmentalist party's first bid for Germany's top job in the Sept. 26 election.

Last week, an Austrian media scientist, Stefan Weber, said that some formulations in Baerbock’s book, titled “Now. How we will renew our country,” published on June 21, were strikingly similar to extracts from other publications. A steady drip of new claims of copied passages followed.

Baerbock’s party called the claims an “attempt at character assassination.” Baerbock herself last week rejected talk of copyright infringement, though she said that many ideas from others flowed into the work.

A number of German Cabinet ministers and others have resigned over recent years following allegations of plagiarism in their doctoral theses, but Baerbock's book wasn't subject to those academic standards and didn’t contain footnotes.

In comments to Thursday's edition of the daily Sueddeutsche Zeitung, Baerbock said she had relied on publicly accessible sources, "but I take the criticism seriously.”

“In retrospect, it would certainly have been better if I had worked with a list of sources,” she added.

The Greens led many polls after Baerbock, 40, was nominated in April. But recent surveys show Merkel’s center-right Union bloc, under Armin Laschet, leading by up to 11 points.

Green missteps have included a poorly presented plan to raise gasoline prices and talk of ending short-haul flights, which they don’t actually aim to ban. Baerbock herself has faced intense scrutiny — she had to correct details in a resume and belatedly declared payments from her party, which she says she wasn’t immediately aware had to be declared, to parliamentary authorities.

Baerbock said that she and the Greens have worked hard to overcome traditional political divisions, but acknowledged that the approach is being tested in a tough campaign — “I also slipped briefly into old trenches.”