People who are interested in third-parties and are interested in a new third-party whether its center-left, or center-right, should look at Teddy Roosevelt and his 1912 Progressive Party. TR was the center-left version of Ross Perot.
Ross Perot ran a strong 1992 center-right third-party campaign against President George H.W. Bush and Governor Bill Clinton. Ross Perot had a strong center-right fiscally conservative reform movement, that was designed to shake up Washington and the political system there. In 1992 Perot and his reform movement, ran against high deficits and a national debt, and an economy that was just starting to come out of recession that still had high unemployment. And had a plan that was designed to lead America back to strong economic and job growth, by first addressing the budget deficit and national debt.
TR was a Progressive and was someone who did believe that America should pay its bills and not run up high deficits and debt, especially when the economy was strong, but he also was a Progressive. And believed that government and even the Federal Government, had a major but not the only role, in seeing that the country moved forward and where everyone could succeed in America. Not just the wealthy and the people who are born to wealth. And believed that the wealthy had too much power and money and the country. While too many Americans struggled just to survive and pay their bills.
Back in 1912 America had a choice between two right-wing parties. The Center-Right Republican Party, that had a progressive Northeastern wing in it that TR was part of, but they were a conservative party. And the Democratic Party that was even to the right of the Republicans, with a Southern Neo-Confederate Nationalist wing in it that had accepted that Civil War was over and slavery was now illegal, but still believed that Africans were inferior to Europeans and therefor African-Americans weren’t entitled to the same rights and freedom, as European-Americans. The Progressive Party under Theodore Roosevelt, was obviously to the left of both the Republican and Democrats. With TR now representing a new and growing progressive movement in the country.