WASHINGTON (AP) — The Latest on the 2016 presidential campaign as candidates in both parties look ahead to Super Tuesday, the biggest single-day haul of delegates on the election calendar (all times local):

9:55 p.m.

Marco Rubio is finishing another marathon day campaigning Sunday, blitzing critical Virginia ahead of Tuesday's pivotal GOP presidential primary on a humorous note.

He is sticking with his all-out assault on leading GOP rival Donald Trump's character, vowing to "never let the Republican Party and conservative movement be taken over by a con artist."

Losing his voice after three sold-out rallies across the state, Rubio brought some new material to the heavily college-age audience of more than 3,000 at Roanoke College in Salem, Virginia, in the southwestern part of the state.

Rubio mocked Trump for his complexion, as he has before, accusing him of having a bad "spray tan."

Prompting cheers and laughter, Rubio said: "Donald is not going to make America great. He's going to make America orange!"

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7 p.m.

Ted Cruz says it's "unfortunate" that Donald Trump won't condemn former Ku Klux Klan leader David Duke, and says a white supremacist group is making robo-calls urging people, "Don't vote for the Cubans in the race."

Trump was asked during CNN's "State of the Union" whether he publicly condemns "the racism of former KKK Grand Wizard David Duke," who recently endorsed Trump.

Cruz told reporters Sunday in Oklahoma City that a white supremacist group is making pre-recorded calls supporting Trump and saying not to support Cuban-Americans like himself and Marco Rubio.

Cruz acknowledges that Trump can't control outside groups, but he says, "We should all be united in saying that the Klan is reprehensible."

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5:45 p.m.

Republican Donald Trump has picked up the endorsement of Alabama Sen. Jeff Sessions.

At a rally with Trump in Huntsville, Alabama, Sessions says he told Trump: "This isn't a campaign. This is a movement."

The GOP senator says "nobody's perfect," but that "at this time in American history, we need to make America great again." He was repeating a Trump slogan.

Sessions had appeared with Trump last August at a rally in Mobile, Alabama.

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5:15 p.m.

Ohio Gov. John Kasich's advisers are downplaying the idea he wants a brokered GOP convention against Donald Trump. It surfaced in a New York Times story this weekend about Republican efforts to stop Trump.

Kasich senior strategist John Weaver says the campaign isn't floating the idea. Instead, he says, the campaign plans to take Trump after March 15, when he expects Kasich to win Ohio and Republican Sen. Marco Rubio to lose his home state of Florida.

Even with an Ohio win, Kasich will face an uphill climb for convention delegates, more so if Trump sweeps the Super Tuesday states this week.

Asked whether his positive message has yet to translate into significant support from voters, Kasich says it's because he's still relatively unknown to voters.

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5:10 p.m.

Coming off a bruising loss in the South Carolina primary, Bernie Sanders is keeping his focus firmly on Super Tuesday and not on his loss Saturday in South Carolina.

Sanders told more than 6,000 cheering people gathered at an Oklahoma City convention center Sunday that he'll need their help to win the general election. He says nothing would please him more than to defeat Donald Trump.

Sanders spoke for more than an hour but avoided mentioning his huge loss to Hillary Clinton Saturday in South Carolina. Instead, Sanders stuck to his standard talking points.

And he repeated his call for Clinton to release transcripts of her paid speeches to Wall Street banks, saying, "If you're going to get paid $200,000 a speech, must be a pretty damn good speech. "

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4:50 p.m.

Hillary Clinton says she's looking forward to debating any one of the Republican candidates, should she capture the Democratic nomination for president.

She rallied several hundred supporters at a historically black medical college in Nashville, Tennessee.

Clinton is looking past Sanders in a return to her early campaign strategy, when she was the clear primary frontrunner.

With Sanders lagging in delegates and likely facing greater losses on Super Tuesday, Clinton's team is beginning to turn their focus to unifying the party. They don't want to risk alienating Sanders backers whose support Clinton will need to win a general election.

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1:30 p.m.

Marco Rubio says Republican front runner Donald Trump is "wrong" to refuse to condemn former KKK leader David Duke.

Trump was asked during CNN's "State of the Union" whether he publicly condemns "the racism of former KKK Grand Wizard David Duke," who was recently quoted equating voting against Trump to treason.

Trump replied he didn't "know anything about David Duke."

He added: "You're asking me a question that I'm supposed to be talking about people that I know nothing about."

Rubio says: "We cannot be a party who refuses to condemn white supremacists and the Ku Klux Klan."

He adds: "Not only is that wrong, it makes him unelectable."

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12:50 p.m.

Hillary Clinton is church-hopping across Memphis in an effort to mobilize African-American voters ahead of Tuesday's primaries.

She's speaking at two churches in the city Sunday and asking worshippers to reject "the demagoguery, the prejudice, the paranoia." She never mentioned GOP front runner Donald Trump's name, but the comments referenced his campaign slogan, "Make America Great Again."

"American has never stopped being great, our task is to make American whole," said Clinton at Greater Imani Cathedral of Faith.

With rival Bernie Sanders trailing in delegates, Clinton is beginning to focus more attention on her potential GOP challengers. Her church addresses, like her South Carolina victory speech, made no mention of the Vermont senator, or his policy plans.

Clinton is trying to rally black voters ahead of the Super Tuesday contests, which take place in a number of southern states. Black voters turned out in a higher percentage in South Carolina on Saturday than in 2008, catapulting Clinton a sweeping win there.

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12:00 p.m.

Hillary Clinton is shifting her focus to Republican front-runner Donald Trump as her party seeks consensus on the best ways to challenge the billionaire's unpredictable nature in a general election.

As Clinton enters the series of "Super Tuesday" contests this week, allies of the former secretary of state, unaffiliated Democratic strategists and the national party are stockpiling potential ammunition about Trump, reviewing reams of court filings, requesting information about his business dealings from state governments and conducting new polls to test lines of attack.

Among the likely options: Questioning Trump's qualifications and temperament to be president, scrutinizing his business practices and bankruptcy filings, and re-airing his inflammatory statements about women and minorities who will be central to the Democrats' efforts in November.

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11:40 a.m.

The national finance co-chair of New Jersey Gov. Chris Christie's suspended presidential campaign is lashing out at the governor for throwing his support behind GOP front-runner Donald Trump, calling the decision "an astonishing display of political opportunism."

Meg Whitman, the president and chief executive officer of Hewlett Packard, says in a statement she will not be joining Christie on Trump's campaign.

She says, "For some of us, principle and country still matter."

Whitman adds that Trump is "unfit to be president" and "a dishonest demagogue who plays to our worst fears.

She's calling on Christie's donors and supporters to reject the newly-united pair.

But Christie is brushing off the statement.

He says in an interview on ABC's "This Week" that the pair remain friends but disagree and "that's OK."

"Meg has always been free to express her views and I honor her," he adds.

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10:15 a.m.

Marco Rubio's campaign is teeming with mainstream Republican officials and donors, and yet Rubio's team concedes that's not enough to stop Donald Trump.

Instead of riding the wave of new support alone, Rubio is now forced to speed up plans for an all-out assault on the billionaire businessman's character.

Rubio had hoped to wait until the chaotic Republican nominating campaign had shrunk to a two-man race. But with a growing sense of urgency among GOP stalwarts to settle on a Trump alternative, the young Florida senator is trying to simultaneously slow Trump and cast himself the savior of the party's future.

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10:00 a.m.

Donald Trump is refusing to disavow his endorsement by David Duke, saying he doesn't know anything about the former Ku Klux Klan leader.

Trump was asked on CNN's "State of the Union" whether he would declare that he didn't want Duke's support, or that of other white supremacists in the presidential election.

Trump says of Duke, "I just don't know anything about him."

Trump likewise says he wouldn't condemn a group that he knows "nothing about." He adds that if he were sent a list of groups he would research them and "certainly" would disavow any if he thought there was "something wrong."

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9:55 a.m.

Congresswoman Tulsi Gabbard says she's resigning the Democratic National Committee to support Bernie Sanders for president.

The Hawaii Democrat tells NBC's "Meet the Press" that she trusts Sanders to consider the consequences of any military action.

Even as she spoke in the live interview, Gabbard's name remained on the DNC web site as vice chair.

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9:32 a.m.

Bernie Sanders says he knows what happened Saturday night when Hillary Clinton clobbered him by roughly 50 percentage points in South Carolina.

He says, "We got decimated, that's what happened."

Sanders said on NBC's "Meet the Press" that his campaign is "looking to the future, not looking back."

The loss in South Carolina underscored Sanders' weakness with black voters, a critical segment of the Democratic electorate. If he loses blacks by similar margins in the Southern states that vote Tuesday, Clinton would likely take a delegate lead difficult for the Vermont senator to overcome.

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8:59 a.m.

John Kasich says Mitt Romney has not asked him to get out of the race for the GOP nomination.

The Ohio governor says on NBC's "Meet the Press" that he and the 2012 Republican nominee have exchanged emails but "nobody's asked me to drop out."

He adds, "that never happened in terms of Mitt trying to tell me, you know, what I need to do with my career."

The New York Times reported that Romney had urged Kasich to quit and let the Republican party coalesce around a candidate other than front runner Donald Trump.

Kasich says he intends to win the Ohio primary March 15. But he adds that if it doesn't happen, it's "ballgame over."

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8:50 a.m.

Whatever the polls, Marco Rubio insists that Donald Trump won't be the Republican presidential nominee. No way, no how.

But the Florida senator — publicly confident but still trailing the 2016 front-runner — also feels compelled to spell out a doomsday scenario for his party if Trump rolls on to victory.

Rubio tells CBS' "Face the Nation" that if Trump wins the nomination, "it will split us and splinter us in a way that we may never be able to recover and the Democrats will be joyful about it."

But Rubio suggests that doesn't matter anyway because Trump won't win the GOP nomination.

He says, "It's not going to happen."

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8:32 a.m.

Sen. Lamar Alexander is backing Marco Rubio for president.

The Tennessee Republican says in a statement that Rubio can "inspire us, win the election and led our country."

Alexander says Rubio is tough on Islamic militants, an efficient administrator and an advocate for veterans.

Alexander is a former governor and secretary of education under President George H.W. Bush.

The endorsement is the latest of a string of nods Rubio has received from members of the Republican establishment. The Florida senator is highlighting endorsements as part of his drive to become an alternative to GOP front runner Donald Trump.

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7:45 a.m.

Ted Cruz doesn't think it will happen, but he's acknowledging that a super showing by Donald Trump on Super Tuesday could perhaps seal the nomination for the billionaire businessman.

Cruz tells CBS' "Face the Nation" that "there is no doubt that if Donald steamrolls through Super Tuesday, wins everywhere with big margins, that he may well be unstoppable."

Republicans will vote in 11 states, with 595 delegates at stake.

Cruz and Marco Rubio are the leading contenders trying to slow down Trump.

Cruz says he's the only one who can beat Trump, and the Texas senator is making this appeal to voters: "I would encourage you, even if you like another candidate, stand with us if you don't want Donald to be the nominee."