Party strategists told ABC News that, though no public polling has been done in the past week, the West Virginia contest remains a tight three-way race.
Some in party leadership are still smarting from the loss in the Alabama senatorial election in which Democrat Doug Jones defeated Moore, a Republican who faced allegations from eight women who have accused him of sexual misconduct when he was in his 30s and, in some cases, the women were in their teens. Moore has denied the claims.
"We all really like President Trump's policies but we know he always doesn't get things right. He recommended that people vote for a guy that was basically accused of pedophilia in Alabama," Blankenship said in an apparent reference to Trump's endorsement of Moore.
The millionaire has poured millions of his own money into the race and has blanketed the state with ads defending his past and attacking Manchin and other Republican candidates.
Taking a page from Trump's 2016 playbook, Blankenship has talked about conspiracy theories, tried to revamp his past, has given his political opponents nicknames like "Little Joe" and went full throttle against Washington, D.C. Strategists point to the recent Fox News debate, where they say he came across as likable and even funny after being painted as villain in political ads.
His seemingly recent rise in support has at least one of the three candidates, Morrisey, going on the offensive just days before the primary.
On Sunday, Morrisey held a press conference where he slammed Blankenship and raised questions about his failure to file a personal financial disclosure form as required by law.
"With two days left, Don Blankenship continues to dismiss the blatant rules to run for Senate," Morrisey said.
"Morrisey's trying to tear Don's house down," Andy Sere, a spokesperson for the Jenkins campaign, told ABC News. "It's not going to work and I think it's pretty clear that he's incredibly worried about the position that he's fallen to."
Democratic PACs have poured in millions, too, for negative ads against Blankenship's opponents — a move which some Republican operatives say have helped boost support for the former coal baron in the state.
Blankenship, meanwhile, is doubling down on his attacks against Senate Majority Leader Mitch McConnell and continues to defend his use of the term "China people."
In a new radio ad, Blankenship says that "the establishment politicians are getting more desperate and more hostile, calling me a bigot, a moron, a despicable character and mentally ill." Then adds, "but even if all this is true, I will do a better job than they will have done."
The ad ends, "send me to the Senate and I will represent West Virginia people not China people. I am an America person and I will put America first."
Ahead of Tuesday's primary, a national Republican operative tells ABC News that candidates are starting to pull out all the stops now that it's "down to the wire."