The liberal Mayor of Budapest Gergely Karacsony and centrist-conservative mayor Peter Marki-Zay have been working on a backroom deal that will lead to one of them withdrawing from the three-person run-off for selecting the six-party opposition’s joint candidate. However, talks seem to have stalled on Wednesday as Karacsony vowed to remain in the race, while Marki-Zay is not planning to withdraw either. A new poll shows that Marki-Zay is closing the gap and is the second most popular candidate among opposition voters.

The two politicians had planned to work in a tandem to squeeze out the winner of the first round of the primary election, Klara Dobrev, who got 34% of the votes. The leftist-liberal candidate of the largest opposition party Democratic Coalition (DK) won in each of the 19 counties states but came in second in the capital behind Karacsony, who won 27% of the votes but performed weakly in the countryside. Beating the odds, Marki-Zay, an outsider without any party backing, got 20% to qualify for the second round, which will be held between October 10-16.

The frantic backroom dealmaking and the clashes between the second and third placed candidates have been a gift to Dobrev as the frontrunner but have also helped Hungary's strongman premier.

Marki-Zay has been the main advocate of creating an anti-Dobrev coalition before the second round of voting as he argues that the opposition has little chance of toppling Viktor Orban’s regime with the wife of unpopular former Socialist Prime Minister Ferenc Gyurcsany.

Many on the opposition landscape agree that Dobrev’s political carrier is tainted by the legacy of Gyurcsany, who is blamed for the economic problems after he came to power in 2004 and for the violent riots two years later.

"It would be a jackpot for Fidesz to select Dobrev" said Marki-Zay in a television debate on September 24, adding that the deputy of the European Parliament would scare away undecided voters.

The ruling party has been mobilizing voters to sign a petition called 'Stop Gyurcsany, Stop Karacsony!' timed for the primaries to distract attention and to dominate public discourse. Fidesz launched a communication offensive saying whoever emerges as winner in the primaries, he or she will be the puppet of Gyurcsany.

Dobrev’s two challengers agreed on Friday that one of them will step down in the run-off and, if elected next year, then the other will be the deputy PM. The two candidates held talks soon after the results of the first round became official.

Karacsony met Marki-Zay in Hodmezovasarhely on Tuesday, but there was no decision on who should withdraw from the race. They suggested that their names should be next to each other in the ballots, but the civil electoral commission set up to oversee the primaries has rejected the idea, arguing that it goes against the principles agreed upon.

"There will be no tandem. We don’t change the rules during the game, that’s what democracy is all about", a leading committee member said. Rewriting rules requires a unanimous vote by all six parties.

The two leaders said they would come up with a joint progamme that does not go against the six-party’s own agenda and which centre-right and centre-left voters would also find attractive.

The talks reached an impasse on Wednesday as Dobrev’s two rivals clashed. Karacsony said he would only resign if hit by a tram, while Marki-Zay also seemed reluctant to leave the race after polls showed him second in the race and closing the gap with Dobrev.

We are going to run separately in the second round, but we are both committed to preserving and strengthening opposition unity, Karacsony wrote on his Facebook page on Wednesday night after yet another round of talks.

Median's latest poll shows Dobrev at 37%, Marki-Zay at 33%, and Karacsony trailing way behind at 24% among decided voters. Budapest's mayor shrugged off the findings in the poll, but observers say it could have far-reaching consequences and determine the outcome of the rivalry between the two.

The primaries have shaken the political balance of power, as more people wanted Viktor Orban to go next year than to stay, according to Median.

With the backing of the largest party network, Dobrev is focusing solely on her campaign, touring the country around the clock. She is winning by huge margins among rural voters. Support for Karacsony and Marki-Zay in cities and among young people is higher.

"The primaries are not about percentages, odds and tactics, but about the historic mission to defeat Viktor Orban and his regime next spring. That's all I care about", Dobrev wrote on social media.

Opinion polls on Wednesday showed that Dobrev would win the three-person race, followed by Marki-Zay in second, and Karacsony trailing far behind in third place. It also showed the centre-right candidate was the least disliked among opposition party supporters.