Reform UK and the Tories would be “unassailable” if they joined forces, according to a pollster.
Techne UK's chief executive Michela Morizzo made the comment as her company's weekly tracker put the two right-wing parties in joint second on 24% each.
Nigel Farage's outfit is up one point from the week before, while Kemi Badenoch's party is down one.
Sir Keir Starmer's Labor is only one point ahead on 25% just six months after he entered 10 Downing Street, down one from the week before.
Ms Morizzo told The Independent: “The Labor Party decline continues this week with Sir Keir Starmer's party losing another point in national vote share dropping down to just 25%.
“This in itself is an almost unheard of low polling share for a governing party, particularly as it has only held power for just seven months.
“Once again this highlights that Kemi Badenoch is still struggling to give her party a strong and well defined vision.
“Further to this it is once again Reform UK who are growing in national vote share to 24%. This is now truly a three-way split for these three parties.
“Finally one must also note that the center right of the Conservatives and Reform UK if placed together hold an unassailable 48 percent. What will this scenario lead to? Only time will tell.”
The Lib Dems are on 13% in the poll of 1,643 British adults that was carried out from January 22-23.
It comes as Mr Farage and Ms Badenoch have both ruled out an electoral pact between their parties.
Speaking earlier this month, the Tory leader said: “Nigel Farage says he wants to destroy the Conservative Party. Why on earth would we merge with that?”
Mr Farage has previously said he wants to engineer a “reverse takeover” of the Conservatives.