Mike Pence, a former vice president of the United States, has formally filed his paperwork to enter the Republican field of candidates for president.
He will now compete against former President Donald Trump, who he held the office of president for four years, from 2017 to 21.
In the current polls, Mr. Trump is far ahead of his rivals.
The 63-year-old Mr. Pence is scheduled to formally introduce his campaign on Wednesday through a speech and video.
Since the Trump supporters' riot at the US Capitol in January 2021, the former governor and congressman of Indiana has distanced himself from his former employer.
When he oversaw the certification of results in Congress, Mr. Trump put pressure on Mr. Pence to revoke Joe Biden's election victory.
However, Mr. Pence declined, angering Trump supporters who were heard chanting "hang Mike Pence" as they stormed the halls of Congress.
In March, the former vice president claimed that Mr. Trump's support for the rioters had put "my family and everyone at the Capitol that day in danger."
