With one month to go until the US presidential election, Vice President Kamala Harris has vowed to shore up the country's manufacturing industry. She made the pledge in her campaign speech in the swing state of Michigan.

Election Day is November 5. The Democratic candidate on Friday led a rally in the city of Flint, once a leading producer of automobiles.

Harris said, "We cannot have a strong middle class without American manufacturing."

She stressed, "We have brought manufacturing back to America" over the last three and a half years "by investing in American industry and American workers."

Harris also said she will make sure the United States, not China, wins the competition for the 21st century.

She vowed to invest in the steel, iron, auto and other industries that built America, and ensure that the next generation of breakthroughs -- from advanced batteries to electric vehicles -- are built in the country.

Early voting for the election has already begun. Harris noted that nearly 2 million ballots are already in the hands of Michigan voters alone. She appealed for support, saying, "If you have received your ballot, please do not wait." She added, "Return it today."

US basketball star Magic Johnson also took the stage. The former NBA player and Michigan native called on voters to elect their first female president, as Mexico has done.