Hillary Clinton is set to become the first major party female nominee for president, but voters in many U.S. states will also see another woman on their ballot in November.
Jill Stein, who like Clinton has not yet been formally nominated by her party, expects to be the Green Party's candidate.
Her policies have some similarities with Clinton's main competitor in the Democratic Party race, Bernie Sanders, including raising the minimum wage, reforming campaign finance and addressing climate change.
"The American people are tired of the rigged economy and the rigged political system that created it," Stein said Wednesday. "The presumptive Democratic and Republican nominees are the most disliked and mistrusted of all time."
The challenge for Stein, and Libertarian Party candidate Gary Johnson, is that in the U.S. national politics is dominated by Democrats and Republicans, and certain rules for presidential elections make it difficult for others to compete.
Stein and Johnson are both pushing for greater inclusion, particularly in the three presidential debates that Clinton and Republican nominee Donald Trump will have beginning in September. A special commission sets the rules for those events, requiring a candidate to appear on the ballot in enough states to have a mathematical chance of winning and to receive 15 percent support in five national polls.
Johnson has said the system is set up to keep Democrats and Republicans in power, while Stein called the debates a "fraud."
"We are fighting to open up the debates, so the American people can know who their choices are," Stein said. "We're calling for a common sense rule for participation -- to include all candidates on enough ballot lines to win the presidency."
States have varying requirements to qualify a candidate for the ballot, mainly involving gathering a set number of signatures by a certain date.
The Green Party says it is already qualified in 20 states and is working on others, while the Libertarians say they are on 32 state ballots so far.
Polling agencies have also started including Stein and Johnson when asking people whom they would pick in an election that included Clinton and Trump. An assortment of national polls from the past few weeks show Johnson getting between 6 and 9 percent in a four-way race, with Stein around 5 percent. Johnson gets as much as 12 percent in polls that only include him, Clinton and Trump.
Johnson's campaign got a boost Wednesday when CNN announced it will air a town hall event next week featuring Johnson and his running mate Bill Weld. Clinton and Trump have already taken part in similar programs on the network during the battle for their party nominations.
Meanwhile, Stein could gain more support with Clinton's official nomination and the subsequent end of the Sanders campaign that had particular success with young people who rallied around his calls for a political revolution. Clinton is trying to pull in as many Sanders supporters as possible, but Stein said in a Huffington Post interview Wednesday that "if the [Sanders] movement gets absorbed inside the Democrats, that's the end of it."
Johnson and Stein are looking to improve upon their showings in the 2012 election when they came in third and fourth place. That year they got nearly 2 million votes combined, but that was well short of the 66 million people who gave another term to President Barack Obama.