Steve Bannon, an architect of President Donald Trump's 2016 election victory, has been charged with fundraising fraud in a campaign to help Trump build his signature wall on the US-Mexico border, the US Justice Department said on Thursday.As a top adviser to Trump's presidential campaign who later served as chief White House strategist, Bannon helped articulate the right-wing populism and fierce opposition to immigration that have helped define Trump's 3-1/2 years in office. Bannon left the White House in August 2017. Bannon was among several people charged with wire fraud in an indictment by federal prosecutors in Manhattan for allegedly defrauding hundreds of thousands of donors through a $25 million crowdfunding campaign called "We Build the Wall."Prosecutors said Bannon received more than $1 million of that money through a nonprofit organization.Trump's signature effort to build a wall along the US-Mexico border - a key 2016 campaign promise - has struggled amid court challenges, logistical hurdles and opposition from Democrats in Congress.In the meantime, more than 330,000 supporters have donated to private fund-raisers and profiteers who have promised to build the wall on their own, according to a 2019 Reuters investigation. Those efforts likewise have met with limited success.The indictment comes as Trump trails in opinion polls behind Democratic challenger Joe Biden ahead of the Nov. 3 presidential election.A spokeswoman for Bannon could not be immediately reached for comment.President Donald Trump, asked for his reaction to the arrest of his former adviser Steve Bannon, said he feels very badly but knows nothing about the fundraising organization involved in the federal criminal case.Bannon has been charged with defrauding Trump supporters in a campaign to help build the president's signature wall along the US-Mexico border.Also charged were Brian Kolfage, Andrew Badolato and Timothy Shea.The donors thought the money would go toward helping to build a border wall, prosecutors said. But Kolfage, whom they described as the public face and founder of the operation, received thousands of dollars that he used to fund a lavish lifestyle.Kolfage is due to appear in federal court later on Thursday in Florida, while Bannon is set to appear in federal court in Manhattan. The other two defendants are due to appear in courts in the Middle District of Florida and Colorado.