(Reuters) - Former U.S. Representative Mark Sanford of South Carolina has abandoned his long-shot bid to challenge President Donald Trump for the Republican presidential nomination in 2020, he said on Tuesday.

FILE PHOTO: U.S. Rep. Mark Sanford (R-SC) questions U.S. Department of Homeland Security Secretary Jeh Johnson on President Obama's executive action on immigration as Johnson testifies at a House Homeland Security Committee hearing on Capitol Hill in Washington, December 2, 2014. REUTERS/Jim Bourg

Sanford, 59, a longtime Trump critic, announced his campaign two months ago. Two other Republicans are running against Trump: former Massachusetts Governor Bill Weld and former U.S. Representative Joe Walsh of Illinois.

Sanford attributed his decision to end his bid to remove Trump as the Republican nominee on the inability to attract attention to his key issue, the national debt.

“I am suspending my race for the presidency because impeachment has made my goal of making the debt, deficit and spending issue a part of this presidential debate impossible right now,” Sanford said in a statement.

The U.S. House of Representatives are conducting an impeachment inquiry into Trump regarding his dealings with Ukraine.

Trump, who remains overwhelmingly popular among Republican voters, is heavily favored to capture his party’s nomination next year.

Sanford lost his seat in Congress last year after a Trump-backed challenger beat him in the Republican primary. He had previously served two terms as South Carolina’s governor, as well as a separate stint in the U.S. House of Representatives.

Sanford had put fiscal conservatism at the heart of his campaign, arguing that the Republican Party’s commitment to reducing spending and cutting deficits has weakened.

“We also need a robust debate on trade and tariffs, our belief in institutions, the president’s tone and a whole lot more, but those things will not happen in a Republican primary embattled with impeachment,” Sanford said.

Once seen as a rising star in the party, Sanford saw his political career wounded when he went missing from South Carolina in 2009 after telling staff that he had left the state to hike the Appalachian Trail.

In reality, as he admitted upon his return, he was in Argentina meeting with his mistress.