WISCONSIN — Republican U.S. Sen. Ron Johnson took to the Wall Street Journal Sunday morning to announce he is running for re-election. 

In his op-ed, "Why I'm Seeking a Third Senate Term," Johnson wrote that he wants to retire but that the U.S. is in "too much peril."

"In 2010 I promised I would always tell people the truth and that I would never vote with re-election in mind. When re-election isn't your primary motivation, those are easy promises to keep. Today, I am announcing I will continue to fight for freedom in the public realm by running for re-election. It is a decision I haven't made lightly. Having already experienced a growing level of vitriol and false attacks, I certainly don't expect better treatment in the future. For my campaign to succeed, I will need the support of every American who values the truth and refuses to allow lies and distortions to prevail," he wrote.

A Johnson candidacy would avoid a wide-open GOP primary in the narrowly divided swing state.

Johnson pledged in 2016 not to run for a third time, but he rescinded that promise and kicked around running again for months, saying circumstances changed when Democrats took full control of Congress and the White House. 

History is on Johnson’s side in the midterm election. The party that does not hold the White House generally gains seats in midterm congressional elections. Former President Barack Obama’s Democratic Party, for example, lost 63 seats in the House and six in the Senate in 2010.

Johnson, who rose out of the tea party movement in 2010, has long been aligned with former President Donald Trump’s hardline policies and politics. The two have remained close following Trump’s defeat, with Trump in April endorsing Johnson for a third term and encouraging him to run.