On 1 October 2021, it became clear that Klára Dobrev and her party, the Democratic Coalition (DK) won the first round with a convincing advantage, obtaining 34.84% and 32 constituencies, respectively.

Out of 106, Dobrev took first place in the competition for prime ministerial candidates in 85 constituencies; she won by a huge margin in the countryside, while the results in Budapest proved to be more balanced.

As a general surprise in mainstream politics and media, independent candidate without any party affiliation Péter Márki-Zay acquired the third place (20.4%), qualifying the second round, while Péter Jakab (Jobbik) – who though was featured as a front-runner in opinion polls – and András Fekete-Győr (Momentum) were eliminated.

[97] Already after the publication of the preliminary results in the eve of 29 September, Péter Márki-Zay initiated negotiations with Gergely Karácsony on the possible withdrawal of one of them in favor of the other, arguing that Klára Dobrev – as the wife of former prime minister Ferenc Gyurcsány, the most divisive politician in Hungary – is the least capable of defeating Viktor Orbán as the prime ministerial candidate of the opposition coalition in the 2022 parliamentary election.

[98] Márki-Zay, in return for his withdrawal, imposed three conditions: accountability of the Fidesz government and its corruption cases, adoption of euro and repeal of the fundamental law.

On the same day, Karácsony himself refused to step back in an interview at Partizán online channel, and offered that Márki-Zay could also be the deputy prime minister in his government after a potential victory in 2022.

He also argued he spent orders of magnitude less money during the campaign than Karácsony, yet he achieved "almost the same result" in the first round.

[100] Jobbik leader and eliminated candidate Péter Jakab also opposed the cooperation negotiations between Karácsony and Márki-Zay.

[103] On the same day, Márki-Zay also organized a street rally, where he said that he believes he is the one who could address most people, but if Karácsony makes a vanity question out of the candidacy, he won't be involved in this "chicken game" and "he will pull the steering wheel aside".

[104] On the next day (4 October), Karácsonyi visited Márki-Zay at Hódmezővásárhely, where they confirmed their intention to run in the second round together and requested the National Primary Election Office (OEVB) for their names to appear next to each other and not below each other on the ballot paper.

According to a survey by Publicus and Republikon, Karácsony, according to Závecz and Medián, Márki-Zay had a better chance of winning over Klára Dobrev in the second round.

[114] Negotiations between them did not reach result in that afternoon, and Karácsony announced neither will step back in favor of the other, three candidates will be on the ballot.

[115] On 7 October, András Fekete-Győr announced that his party, the Momentum Movement will support Márki-Zay in the second round.

[120] Abandoning its former neutral position, the presidium of MSZP called for support of Márki-Zay on 14 October, two days before the end of the second round, despite the fact that many prominent members had previously endorsed Klára Dobrev.