The use of the #NeverTrump hashtag grew on Twitter on Monday as detractors of Republican presidential front-runner Donald Trump fretted over his momentum on the eve of Super Tuesday election contests.
On Twitter, the top influencer, or person who received the most engagement on their #NeverTrump tweets, was Trump rival Marco Rubio, according to online research firm Hashtagify.me.
The senator from Florida and real estate billionaire Trump are engaged in an increasingly personal battle of insults on social media before voters in more than a dozen states select their party's nominee to run for the White House in November.
Rubio began using the tag on Friday, tweeting: "Donald Trump is a con artist - and he cannot be our nominee. #NeverTrump." The tweet received more than 8,000 "likes" and 5,100 retweets.
He repeated the tag in three more tweets over the weekend, with each one getting several thousand likes or retweets.
A spokeswoman for the Trump campaign did not immediately return calls for comment.
Another major influencer on the tag was conservative commentator Glenn Beck (@glennbeck), even though he has used it just once, on Sunday. Beck supports U.S. Senator Ted Cruz of Texas in the campaign.
Still, Beck's post - "Praying for this great country. Praying for a true constitutionalist! God bless (an emblem for the American flag). #NeverTrump #CruzCrew" - proved influential, getting retweeted nearly 1,000 times and liked nearly 2,000 times.
Traffic on the hashtag was dominated by users who identify as conservative or Republican, most expressing vexation with the front-runner.
Many tweets focused on Trump's CNN interview on Sunday, when he declined to repudiate an endorsement from former Ku Klux Klan leader David Duke. Trump later said he did not hear the question properly because of a defective ear piece.
Whitney Westerfield (@KyWhitney), a Republican state senator from Kentucky, tweeted on Monday, "Wow. Trump blaming his failure to repudiate the hatred & extremism of the KKK on a #BadEarpiece. #NeverTrump."
"No, the white supremacist/David Duke/KKK question isn't hard. Reject their support & denounce their hate. Again & again & again. #nevertrump," said Stephen Hayes (@stephenhayes), a writer for the Weekly Standard, a weekly conservative magazine.
Trump supporters have countered with their own hashtag: #AlwaysTrump.
"We must continue to fight on social media, the Peoples Revolution, the strongest tool right now! #TRUMP2016 #AlwaysTrump," wrote Trump supporter Linda Alexander (@noopdoggy).
Still, the #NeverTrump hashtag was winning the trending battle, seeing roughly twice the traffic as #AlwaysTrump on Monday, according to social media analytics firm Zoomph.
(Reporting by Gina Cherelus; Editing by Dan Burns and Grant McCool)