WASHINGTON, Jan 9 (Reuters) - Two-term Wisconsin Republican U.S. Senator Ron Johnson, a staunch ally of former President Donald Trump, reversed course and announced on Sunday that he now intends to run for a third term, rather than retire as previously planned. Johnson - who as the former chairman of the powerful Senate Homeland Security and Government Affairs Committee once held a controversial hearing to entertain baseless conspiracy theories that the 2020 presidential election had been stolen - wrote in the Wall Street Journal he felt compelled to run again because he thinks America "is in peril." "Much as I’d like to ease into a quiet retirement, I don’t feel I should," Johnson said in his op-ed. "Countless people have encouraged me to run, saying they rely on me to be their voice, to speak plain and obvious truths other elected leaders shirk from expressing—truths the elite in government, mainstream media and Big Tech don’t want you to hear." Johnson was among a handful of U.S. Republican senators who initially had planned to reject certifying some of the 2020 presidential election results in key swing states on Jan. 6. 2021. Wisconsin is a battleground state closely fought between Republicans and Democrats. However, after the election certification was interrupted on Jan. 6 by throngs of Trump supporters who stormed the U.S. Capitol, Johnson retreated from his plans and did not issue any objections. Since the riots, more than 725 people have been arrested in connection with the deadly attack. Johnson has since faced criticism after he peddled a debunked conspiracy theory arguing leftists posing as Trump supporters played a role in the Jan. 6 attack. He has also cast doubt on the safety of COVID-19 vaccines, opposed a vaccine mandate, and he hosted a panel several months ago that featured people who claimed they were harmed by the vaccine. Johnson announced his tentative retirement plans from the U.S. Senate in March 2021, just one day after he single-handedly delayed debate on President Joe Biden’s $1.9 trillion COVID-19 relief bill for 11 hours. However, in his op-ed on Sunday, he said neither he nor his wife had anticipated "the Democrats’ complete takeover of government and the disastrous policies they have already inflicted on America and the world."