Supporters of Democratic presidential candidate Bernie Sanders listen as he delivers remarks at a campaign rally in Washington, D.C., on Thursday, June 9, 2016. Photo by Kevin Dietsch/UPI | License Photo

Democratic presidential candidate Bernie Sanders delivers remarks at a campaign rally in Washington, D.C. on June 9, 2016. Sanders said he will do everything in his power to defeat the Republican presumptive nominee Donald Trump. Photo by Kevin Dietsch/UPI | License Photo

Supporters of Democratic presidential candidate Bernie Sanders listen as he delivers remarks at a campaign rally in Washington, D.C., on Thursday, June 9, 2016. Photo by Kevin Dietsch/UPI | License Photo

A woman holds a painting of Democratic presidential candidate Bernie Sanders as he delivers remarks at a campaign rally in Washington, D.C., on Thursday, June 9, 2016. Photo by Kevin Dietsch/UPI | License Photo

Democratic presidential candidate Bernie Sanders delivers remarks at a campaign rally near Robert F. Kennedy Stadium in Washington, D.C., on Thursday evening, June 9, 2016. Sanders said he will do everything in his power to defeat the Republican presumptive nominee Donald Trump. Photo by Kevin Dietsch/UPI | License Photo

WASHINGTON, June 9 (UPI) -- By listening to him speak, you might not even be able to tell that Democratic hopeful Bernie Sanders is a man facing a perilously steep climb to the mountaintop.

The Vermont senator kept up his fiery campaign rhetoric outside Washington's Robert F. Kennedy Stadium on Thursday evening, just hours after meeting with President Barack Obama about the sustainability of his continuing White House bid.


"Let me thank all of you for being part of the political revolution," Sanders said at the start of his speech, which was met with chants of, "Thank you, Bernie!"

"Here we are in mid-June, and we're still standing!" he added.

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Sanders touched on all the usual issues -- the economy, health care, education, foreign affairs, LGBT rights and taxes -- but is now doing so at about half strength after laying off half of his staff Tuesday after he lost the critical California and New Jersey primaries.

One difference, though, is that Sanders' fiery rhetoric has largely softened against Hillary Clinton and pivoted against Republican candidate Donald Trump -- the GOP's lone remaining candidate.

"I look forward to meeting with [Clinton] in the near future to see how we can work together to defeat Donald Trump and create a government that represents all of us and not just the 1 percent," he said after his meeting with Obama.

In the same vein, Sanders took multiple shots at other Republican office-holders, saying they should "get out of politics" for trying to "suppress" minority, elder and LGBT voters.

Sanders' speech Thursday was given five days before the final presidential primary in the United States -- in Washington, D.C. -- on June 14. The candidate has promised to continue fighting through the Democratic National Convention in Philadelphia next month -- despite the fact that Clinton appears to have crossed the threshold needed to win the party's nomination.

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Sanders has previously said he hopes to persuade some of the superdelegates behind Clinton to switch their support to his campaign -- something that could happen when the convention begins July 23. A big enough switch could give Sanders enough support to deny Clinton the nomination, but such widespread changes-of-heart from unpledged superdelegates would be unprecedented in American politics.

Regardless of who the Democrats nominate, Sanders says he will certainly be part of the fight to derail the Trump campaign.

"He doesn't like to brag because he's a modest guy," he said when criticizing the billionaire's stated position that climate change is an overemphasized matter. "We are the custodians of this planet. There isn't another planet. This is it. Destroy this one and our children and grandchildren have no place else to go."

Following his White House meet earlier Thursday, Sanders thanked President Obama and Vice President Joe Biden for remaining neutral in the Democratic race. Obama said he wanted to meet personally with Sanders before formally endorsing Clinton.

"Real change never takes place from the top down," Sanders said Thursday evening. "It always takes place from the bottom up."