Accepting the Democratic Party's presidential nomination Thursday, U.S. President Barack Obama told voters they “face the clearest choice of any time in a generation” when they go to the polls this November — a “choice between two different paths for America.”

President Obama took the stage at the Democratic National Convention in Charlotte, North Carolina Thursday night to chants of “four more years.” He told Americans he will not “pretend” the path he is offering is “quick or easy.” He said “the path we offer may be harder, but it leads to a better place.”

Mr. Obama said he is asking the nation to rally around a set of goals in manufacturing, energy, education, national security and the deficit that will “lead to new jobs, more opportunity and rebuild this economy on a stronger foundation.”

The president's goals include creating one million new manufacturing jobs by the end of 2016, doubling exports by the end of 2014 and cutting net oil imports in half by 2020. He is also pledging to cut the nation's deficit by more than $4 trillion over the next ten years.

Mr. Obama's speech comes just nine weeks ahead of the November 6 general election. Mr. Obama and Republican challenger Mitt Romney are in a virtual tie in opinion polls.

Earlier Thursday, the Democrats formally nominated Mr. Obama's running mate, Joe Biden, for vice president. Speaking at the convention Thursday night before Mr. Obama, Biden accepted the nomination and shared details of his experience working with the president. He said he has gotten to see firsthand that Mr. Obama's “profound concern for the average American” is what drives him. He said the United States is on a mission to move forward “from doubt and downturn, to promise and prosperity.” He said it's a “mission we will continue and a mission we will complete.”

Biden was nominated by his son, Beau, who called him a hero. Images of the vice president showed him tearing up as his son spoke.

Also Thursday, Mr. Obama held a conference call with supporters who were supposed to see him in person as he delivered his acceptance speech.

Convention organizers had planned to stage the president's speech at a 74,000-seat outdoor football stadium in Charlotte, North Carolina. They scrubbed those plans and moved the speeches to a much smaller indoor arena, citing the threat of thunderstorms.

Mr. Obama said during Thursday's conference call that the move was “disappointing” but he could not put the safety of supporters and volunteers at risk.

He also told supporters he expected a close race against Republican challenger Mitt Romney. He said Mr. Romney's campaign was preparing to release a “barrage” of negative ads.