Hillary Clinton went on the offensive against Donald Trump, tying his campaign to the “alt-right” political ideology embraced by many white supremacist groups in the US.

She accused Mr Trump of building his campaign off “prejudice and paranoia”, positioning his entrance into the mainstream political process as unprecedented and painted a picture of dark shadows cast over the future of the country.

Ms Clinton appeared at a community college in Reno, Nevada, a week after Mr Trump hired a new campaign chairman, Stephen Bannon – the executive chairman of the right-wing news site Breitbart, known for its appeal to white nationalists.

“[Donald Trump] is taking hate groups mainstream and helping a radical fringe take over the Republican party,” she said. “His disregard for the values that make our country great is profoundly dangerous.”

The so-called “alt-right” movement was validated by the Trump campaign with the August hiring of Mr Bannon. Ms Clinton called Mr Bannon’s position as chief executive of Mr Trump’s campaign a “landmark achievement” for alt-right groups.

Hillary Clinton campaign ad attacks Donald Trump over KKK ties

“This is not conservatism as we have known it. This is not Republicanism as we have known it,” Ms Clinton said of Breitbart. “These are racist ideas, race-baiting ideas – anti-Muslim, anti-immigrant, anti-woman. All key tenets making up the emerging racist ideology known as the ‘alt-right’.”

The former Secretary of State took aim at Mr Trump’s week-long effort to reach out to black voters. She called out the apparent New York billionaire for describing black communities in “insulting and ignorant” terms.

“It really does take a lot of nerve to ask people he’s ignored and mistreated for decades, ‘What do you have to lose’, because the answer is, 'Everything',” she said.

“Trump is reinforcing harmful stereotypes and offering a dog whistle to his most hateful supporters.”

Donald Trump calls Hillary Clinton a 'bigot'

Kellyanne Conway, the latest Trump campaign manager, accused Ms Clinton of lying about Mr Trump and offering no substance in her speech.

"Today proved to the American public what we have known all along: Hillary Clinton has no hope, no vision and no ideas for the future of our country," she said.

Donald Trump issued his retort via Twitter.

“Just watched recap of #CrookedHillary’s speech. Very short and lies. She is the only one fear-mongering,” he said of the speech that spanned more than a half-hour.

He continued: “[Her] short speech is pandering to the worst instincts in our society. She should be ashamed of herself!”

The Clinton campaign released a video Wednesday afternoon as a prelude to the speech. The video is a montage of prominent white supremacists – such as former Ku Klux Klan Grand Wizard David Duke – giving their endorsements for Mr Trump.