The suspect in a mass shooting at a synagogue in Pittsburgh that killed 11 worshipers has been charged on a total of 44 counts, up from 29 counts previously, according to a federal indictment filed on Wednesday.

The charges against Robert Bowers, the suspect in what is believed to be the deadliest attack on Jews in the United States in recent history, include religious hate crimes, firearms charges and causing injury to police officers. Bowers is due to appear at a second hearing in federal court in Pittsburgh on Thursday.

The attack, believed to be the deadliest against Jews in the United States in recent history, has fueled a fierce political debate about white nationalism and anti-Semitism ahead of hotly contested U.S. congressional elections next week.

Prosecutors have said they will seek the death penalty.

The synagogue attack has heightened a national debate over Republican U.S. President Donald Trump's rhetoric, which critics say has contributed to a surge in white-nationalist and neo-Nazi activity. His administration denies he has encouraged far-right extremism and is instead attempting to unify America.

Amid the first funerals for victims on Tuesday, Trump visited Tree of Life. Thousands protested his presence in the city, accusing him of using rhetoric that has fueled anti-Semitism in America.

Several thousand protesters, an ethnically mixed crowd of all ages, held an anti-Trump rally about a block away from the synagogue just as his visit began, singing Old Testament psalms and carrying signs with such slogans as: "We build bridges not walls."