Sally Kohn is an activist, columnist and television commentator. Follow her on Twitter @sallykohn . The opinions expressed in this commentary are hers.

(CNN) Dr. Jill Stein is without a doubt a bold progressive leader. But let's face reality: A vote for Jill Stein is a vote to elect Donald Trump.

In a September 2016 NBC News/Wall Street Journal/Marist poll , when registered voters were given the choice between Hillary Clinton and Donald Trump, 46% chose Clinton while 41% chose Trump. But when Jill Stein and Gary Johnson were added as options, 9% of registered voters chose Johnson and 3% chose Stein. Meanwhile Trump's support dropped two points to 39%. But Clinton's? Her support dropped 5 points to 41%.

In Arizona, a state in play in this election that the Clinton campaign is making a strong effort to win, early September polling shows Clinton at 41% and Trump at 40% with registered voters. But when Stein and Johnson are options? Arizonans throw 13% of their support behind Johnson and 4% to Stein -- and give 37% each to Clinton and Trump, cutting Clinton's small lead down to a statistical dead heat. It's clear -- at least in these two states -- that support for Johnson and Stein most clearly hurts Clinton and helps Trump.

In a national Quinnipiac poll last week , millennial likely voters supported Clinton over Trump by a 55-34 margin. But when Stein and Johnson were included in the survey, Clinton received just 31% support by likely voters between 18 and 34. Upon further analysis , it's clear that Stein is the one mostly taking votes away from Clinton.

Stein understandably sees herself as taking the baton from the progressive revolutionary campaign of Bernie Sanders. There's only one problem with that: Sanders himself handed the baton to Hillary Clinton.

Photos: The women who have run for president Photos: The women who have run for president American feminist reformer Victoria Woodhull was the first woman to run for U.S. president from a nationally recognized ticket as the candidate of the Equal Rights Party in 1872. Woodhull was also one of the first female stockbrokers on Wall Street. Hide Caption 1 of 19 Photos: The women who have run for president Belva Lockwood was the first woman to practice law in front of the U.S. Supreme Court. She ran for president in 1884 and 1888 on the Equal Rights Party ticket. Hide Caption 2 of 19 Photos: The women who have run for president Gracie Allen made a farcical run for president in 1940. Campaigning under the Surprise Party platform, Allen -- with husband George Burns -- went on a whistle-stop tour of the country. Hide Caption 3 of 19 Photos: The women who have run for president Sen. Margaret Chase Smith was the first woman to serve in the House of Representatives and Senate. She was also the first woman to be placed in nomination for the presidency at a major party's convention (the Republican National Convention in 1964). Hide Caption 4 of 19 Photos: The women who have run for president Charlene Mitchell was the Communist Party USA nominee for president in 1968 and also challenged Daniel Patrick Moynihan, D-New York, for the Senate in 1988. Hide Caption 5 of 19 Photos: The women who have run for president U.S. Rep. Shirley Chisholm announces her entry for Democratic nomination for the presidency in 1972 in Brooklyn, New York. Chisholm was the first African-American female candidate from a major party. Hide Caption 6 of 19 Photos: The women who have run for president Linda Jenness was the Socialist Workers Party candidate for president in 1972. Hide Caption 7 of 19 Photos: The women who have run for president Margaret Wright was the Peace and Freedom Party presidential candidate in 1976. Her running mate was Dr. Benjamin Spock. Hide Caption 8 of 19 Photos: The women who have run for president Maureen Smith was the Peace and Freedom Party presidential candidate in 1980. Hide Caption 9 of 19 Photos: The women who have run for president Feminist activist and writer Sonia Johnson ran in 1984 as the presidential candidate of the U.S. Citizens Party, Pennsylvania's Consumer Party and California's Peace and Freedom Party. Hide Caption 10 of 19 Photos: The women who have run for president Lenora Fulani ran for president in 1988 and 1992 as a candidate of the New Alliance Party. Here, she holds a news conference at Atlanta City Hall in July 1988. Hide Caption 11 of 19 Photos: The women who have run for president Elvena Lloyd-Dufﬁe ran as a Democratic candidate against incumbent Bill Clinton in 1996. Hide Caption 12 of 19 Photos: The women who have run for president Elizabeth Dole unsuccessfully sought the GOP nomination for president in 2000. She is a former U.S. senator from North Carolina and served as U.S. secretary of transportation under Ronald Reagan and secretary of labor under George H.W. Bush. She is the wife of former Sen. Bob Dole, the 1996 Republican nominee for president. Hide Caption 13 of 19 Photos: The women who have run for president Former Sen. Carol Moseley-Braun of Illinois sought the 2004 Democratic presidential nomination. Hide Caption 14 of 19 Photos: The women who have run for president Hillary Clinton, the presumptive Democratic nominee for 2016, noted in 2008 that the glass ceiling had "18 million cracks in it" -- a reference to the number of votes she received in the 2008 Democratic primary before conceding the race to Barack Obama. Hide Caption 15 of 19 Photos: The women who have run for president Cynthia McKinney was the Green Party presidential candidate in 2008. McKinney was a six-term Democratic congresswoman from Georgia before running for president. Hide Caption 16 of 19 Photos: The women who have run for president Roseanne Barr announces she is a candidate for president on "The Tonight Show with Jay Leno" in 2011. She won the 2012 nomination of the Peace and Freedom Party. Hide Caption 17 of 19 Photos: The women who have run for president Dr. Jill Stein is the 2016 Green Party presidential candidate. She was also the party's presidential candidate in 2012. Hide Caption 18 of 19 Photos: The women who have run for president Former Hewlett-Packard CEO Carly Fiorina marches with her family in the Labor Day parade in 2015 in Milford, New Hampshire. Fiorina unsuccessfully sought the GOP presidential nomination in 2016 and then briefly joined Sen. Ted Cruz as his running mate before he suspended his campaign. Hide Caption 19 of 19

"This election is about which candidate understands the real problems facing this country and has offered real solutions," Sanders said in his speech at the Democratic National Convention in August. "By these measures, any objective observer will conclude that -- based on her ideas and her leadership -- Hillary Clinton must become the next president of the United States. The choice is not even close."

As I said when I endorsed Senator Sanders during the primary, he and Hillary Clinton agree on 90% of issues. Which is just true -- of them and of most liberals and progressives and left-of-center folks. Including Jill Stein.

For instance, while the website insidegov.com does rank Hillary Clinton as, on average, slightly more conservative than Stein, according to the site, on issues ranging from keeping abortion fully safe and legal to supporting strong environmental regulations to opposing restrictions on voting rights, Clinton and Stein are in lockstep.

Both Clinton and Stein believe in government spending to stimulate economic recovery, agree that taxes on the very rich are far too low, and oppose privatizing Social Security. Clinton and Stein both support a path to citizenship for undocumented immigrants and they both oppose the Trans-Pacific Partnership trade deal.

And incidentally, Jill Stein believes England's xenophobic Brexit vote was a win for "self-determination." And she also believes that exposing kids to wireless internet access in schools is dangerous for their brains. So there are some things she and Hillary Clinton most definitely do not agree on.

JUST WATCHED What the Green Party's Jill Stein believes in 2 minutes Replay More Videos ... MUST WATCH What the Green Party's Jill Stein believes in 2 minutes 01:59

Stein has said , "I will feel horrible if Donald Trump is elected, I will feel horrible if Hillary Clinton is elected, and I feel most horrible about a voting system that says: Here are two deadly choices, now pick your weapon of self-destruction."

But Stein wildly misrepresents Clinton -- and her own proximity to many of Clinton's positions -- by lumping her into such a vivid generalization. I know that Jill Stein supports the legalization of marijuana, but if she thinks that Trump's flagrantly hateful and destructive agenda is remotely akin to anything Clinton stands for and believes, Stein must be high.

Hillary Clinton is not perfect. But she has spent her entire career working for the very principles of equality and inclusion that Donald Trump has vowed to destroy. And for Latino immigrants and Muslims and working moms and young black men and women fed up with police violence, the difference between a Hillary Clinton presidency and a Trump presidency is too vast to describe with words.

To those of you considering voting for Jill Stein, I suspect most of you desperately do not want Donald Trump to be president. But for whatever reason you don't like Hillary Clinton.

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You should give that some thought -- especially if you enthusiastically supported Barack Obama in 2008 and 2012, who in campaigning and certainly in governing has proven himself pretty much the ideological equal of Clinton in 2016. If you liked him, but don't like her, ask yourself why. And if it boils down to "personality," interrogate that, too.

For the record, while a lot of us loved Bernie Sanders' positions, he wasn't the most likable candidate, either. But none of us seemed to mind that. Why?

Either way, I would love to be able to persuade you to embrace Hillary Clinton -- but even if I can't, please don't help Donald Trump win.

Earlier this month, New Hampshire Sen. Jeanne Shaheen explained what's at stake. "What happened in 2000 is Al Gore lost New Hampshire by about 7,000 votes, and 19,000 people voted for Ralph Nader," she said at an event with Sen. Sanders. "And we got George W. Bush, and we got the war in Iraq."

Meanwhile, the Democratic Party isn't perfect, either, but it still is the best vehicle for advancing progressive policy in America today -- especially if we actively engage with it. Joshua Holland points out how the Working Families Party is a good example of this -- not running symbolic candidates that perpetually lose, but strategically cross-endorsing mainstream Democratic candidates in order to be able to lay claim to a share of their victory and thus influence over their agendas. It has worked -- certainly in shifting New York City Democratic politics to the left and, increasingly, statewide.

By the same token, the Democratic Party needs to change nationally as well. This can't happen if progressives don't engage. Bernie Sanders proved this point by running in the Democratic primary -- and his campaign had an indelible influence on the Democratic Party platform this year as well as several policy shifts on the part of Clinton. And the Progressive Change Campaign Committee has worked closely with the Clinton campaign to elevate progressive issues, including debt-free college, expanding Social Security benefits, and holding Wall Street accountable with tough reforms.

If we want to continue to push the Democratic Party to be a force for progressive change, we need to be part of the conversation -- not marginalize our voices and our votes in some fringe party.

We cannot afford to elect Donald Trump president. The consequences would be unthinkable. Fortunately, we have a great alternative -- a feminist who believes in racial justice and progressive economic policy, who wants to make college debt-free and expand our vital social safety nets. That candidate is Hillary Clinton. Vote for Hillary Clinton on November 8 and ensure that Donald Trump is defeated. Otherwise you risk waking up on November 9 with your conscience very much full of regret.

(Note: A previous version of this article said that the Progressive Change Campaign Committee had endorsed Clinton. In fact, the organization has not, at this point, endorsed Clinton.)