Until recently, few people outside of Pennsylvania had heard of Kathy Barnette.
The political commentator, who is running to become the Republican candidate for an open Senate seat in November, was languishing in the polls before Tuesday's primary election. As such, the two established Republican candidates paid her little attention.
That has all changed now as Ms Barnette, whose Twitter account is littered with incendiary comments, many of them disparaging toward Islam, has pulled even with Dr Mehmet Oz, who is well known for his The Dr Oz Show, and David McCormick, a former hedge fund manager.
Two separate polls, one by Fox News, the other by Trafalgar, show Ms Barnette in a near statistical dead heat with the better-funded and better-known candidates.
Her last-minute surge has jolted the Republican Party, which fears she would be unelectable in a race against a Democratic candidate in November.
"Kathy Barnette will never be able to win the General Election against the Radical Left Democrats," former president Donald Trump said in a statement last week.
Ms Barnette's campaign did not respond to requests for an interview.
Speaking on “Fox News Sunday” ahead of Tuesday’s primary, Ms Barnette said the “overwhelming majority” of the comments for which she’s now being criticised are old and not complete thoughts and that she hasn’t embellished her record as critics say.
“They’re mad because I didn’t ask for permission to be in this space,” Ms Barnette said. “I just walked in because this is my country, and our country is in trouble.”
According to the Fox News poll, Dr Oz is leading with 22 per cent, followed by Mr McCormick with 20 per cent and Ms Barnette with 19 per cent. The margin of error for the poll is three per cent.
Mr Trump, himself known for his "Muslim ban" that sought to restrict travel from 13 majority-Muslim and African nations, said Ms Barnette had said things in the past that had "not been properly explained or vetted".
He did not, however, condemn her seemingly Islamophobic Twitter posts, which include multiple false claims that former president Barack Obama is a Muslim, and said she will "have a wonderful future in the Republican Party" if she can explain those comments.
"And I will be behind her all the way,” Mr Trump said.
Ms Barnette also said Mr Obama “loves all things homosexual” and that Islam “should be banned in the USA.”
The Pennsylvania Senate race is seen as crucial in November's midterms. The seat is presently held by Republican Pat Toomey, who is not seeking re-election.
If the Democrats can secure a win, they may be able to gain control of the evenly divided Senate.
Though they currently have a nominal majority in the upper house, thanks to Vice President Kamala Harris’s tie-breaking role, they have no practical mandate as conservative Democrat Joe Manchin often sides with Republicans.
Ms Barnette’s popularity began rising after she released a video describing how she was a product of rape and why she is still anti-abortion.
The video comes after a leaked Supreme Court ruling revealed the nation's top court is likely to scrap federal protections for women seeking abortions.
The four-minute video has more than 1.3 million views and has helped Ms Barnette to win the backing of conservative groups such as Catholic Vote.
Ms Barnette’s ascendancy has caught her opponents flat-footed and forced them to alter campaign strategies just days before Tuesday’s primary.
“It’s reprehensible that she would tweet out something that is defamatory to an entire religion,” Dr Oz told The Associated Press on Saturday.
“This state was based on religious freedom. I’m proud as a Pennsylvanian to uphold those founding beliefs that every faith has its merits.”
For months, Dr Oz and Mr McCormick waged vicious attacks against each other trying to court Mr Trump’s approval and win the Senate primary.
Dr Oz, who made a fortune in television and has pumped millions of dollars into his own campaign, eventually won Mr Trump's endorsement.
That Dr Oz and Mr McCormick paid so much attention to each other likely allowed Ms Barnette to sneak up in the race, said Jessica Taylor, the Senate and Governors editor at The Cook Political Report that analyses US political campaigns.
“What is stunning is that she has done this with very little money,” Ms Taylor told The National. “I think she's been outspent by something like 350 to one."
