Democratic presidential candidates Hillary Clinton, Martin O'Malley (second from left) and Sen. Bernie Sanders, I-Vt. (right) are greeted by Senate Minority Leader Harry Reid in Las Vegas. (AP/John Locher)

LAS VEGAS — The room vibrated with the sound of screams and noisemakers that are probably more at home on a soccer field than the ballroom of the MGM Grand. Supporters revved up their engines as they waited for Hillary Clinton, Martin O’Malley and Bernie Sanders to speak, cheering for their candidates, and even booing their rivals on occasion.

But it was the Sanders boosters who were loudest, maybe because they carried the red and bright yellow horns, or maybe because they were eager to be heard in a state where Sanders is fighting for relevance.

After an hour of rowdy back and forth between the two sides at the Nevada Democratic Party’s “Battle Born Battleground” dinner, a disembodied voice called out a reminder to the crowd: “Remember to respect all the candidates as they do their speeches.”

Clinton comes into this contest with significant advantages. She won the state in 2008 and has the edge to win it a second time. She began organizing and campaigning here earlier and with greater intensity than Sanders. Clinton holds a double-digit lead over Sanders in the most recent poll.

Still, the former secretary of state also faces an energized opposition — many of them younger voters and caucuses who she will need if she is the nominee.

“I need you,” she told the room. “Because you are the first line of defense.”

The statement is true for Clinton in more ways that one.

The Feb. 20 caucuses are not just the first primary contest in the West — following closely on the heels of the first two nominating states, Iowa and New Hampshire. But Nevada is also a state where a show of strength for Clinton could effectively dash Sanders’s hopes of winning the nomination even if he has a stronger than expected showing in Iowa, or wins in New Hampshire.

Nevada will be the first test of strength in the West and the first to test the ability of Democratic candidates to reach out to a rapidly growing population of Latino voters.

Taking the stage to a full, noisy room, Clinton seemed to draw on the energy, calling out her Republican opposition by name, and making pointed overtures to Sanders supporters that she, too, is on their side, but is more prepared than other Democrats running to do the job.

Clinton promised to stand her ground and she told the crowd that she is the candidate that moneyed special interests really fear.

“You can also count on me to stand my ground especially when it comes to those powerful interests that are holding back American families,” Clinton said. “If Republicans weren’t worried why are hedge fund billionaires already running ads against me?”

As she spoke, the crowd remained divided. Sanders supporters shuffled their seats, others raised their signs and at times grumbled vocally. At one point, campaign organizers walked through the aisles gesturing with a finger to the mouth that supporters should express their disagreement with Clinton silently.

“Some of them might not have been to a rally before,” noted a Sanders supporter and volunteer, Peggy Bennink, 69, of Summerlin. “I think they needed to be guided."

But Bennink added, as much as she hopes Sanders will win, "if he doesn't prevail, then we will support Hillary."

Sanders used his remarks to try to make the case that he could energize more voters in the fall, citing the large turnouts he’s had at his campaign rallies, particularly among younger voters.

He, Clinton and O’Malley all share the goal of defeating Republicans and “right-wing extremism,” Sanders said.

“But let me very clear: That result will not happen with establishment politics and establishment economics,” he said. “We will not succeed unless we galvanize the American people. … We need a Democratic party that makes it clear to every worker in this country that we are on their side and we are prepared to take on the billionaire class.”

Clinton has often made the case that she is the better-rounded and more experienced candidate, saying Democrats should nominate someone to fight for them “not just on a few issues but on all the complex challenges we face.”

Her suggestion seemed to be that Sanders has run a more one-dimensional campaign focused on economic issues.

Though the candidates spoke separately, the evening did highlight several policy differences among the contenders.

Clinton cited progress made on health care under President Obama and warned against “tearing up the Affordable Care Act.” That was a not-so-subtle jab at Sanders, who has proposed moving to a single-payer system.

During his remarks, Sanders credited Obama for making progress in reducing the number of uninsured but said “we must do better.”

“The time is long overdue for this great country to join to the rest of the industrialized world and pass a Medicare for all single-payer program,” Sanders said.

Clinton also took a shot at Sanders’s proposed college affordability plan, which would make tuition free at public universities and colleges for all students. Taxpayers shouldn’t “pay for Donald Trump’s kids to go to college for free,” Clinton said.

Sanders also recapped some of his plans to reform Wall Street, which he laid out in a speech Tuesday in New York. Among the central thrusts of his plan is breaking up banks deemed “too big to fail.” He also supports the reinstatement of a modern Glass-Steagall Act to separate commercial banking, investment banking and insurance services — a move Clinton has not embraced.

O’Malley continued to make the case that he would bring “new leadership” to the White House and highlighted his executive experience as governor of Maryland and mayor of Baltimore.

O’Malley also spoke out against a new wave of deportation raids that the Obama administration has launched against migrant families from Central America.

“This is not consistent with who we are as a country,” O'Malley said. “We must stop ripping families apart and once and for all put an end to these mindless deportations.”

Like the other Democrats, he directed his most pointed barbs at the Republican presidential hopefuls, including Donald Trump.

O’Malley noted that Trump has said that wages are too high in the country.

“Donald Trump’s opinion of himself, that’s too high,” O’Malley said to the delight of the crowd.