The SRS-led coalition refused to cede power, leading to a chaotic situation in which both sides claimed to be the municipality's legitimate government.

In June 2008, Martinović and local DSS leader Dragan Božić announced a new coalition that would have had a one-seat majority in the municipal assembly.

The DS's attempts to form a coalition with the DSS and the Socialist Party of Serbia (SPS) also failed, and the assembly was dissolved for a repeat election in November.

[13] While the overall results of the election were inconclusive, the For a European Serbia alliance led by the DS ultimately formed a coalition government with the Socialist Party, and the Radicals remained in opposition.

[14][15] The Radicals experienced a serious split in late 2008, with several members joining the more moderate Serbian Progressive Party under the leadership of Tomislav Nikolić and Aleksandar Vučić.

Martinović strongly opposed a late 2008 draft of the Statute of Vojvodina, saying it was designed to "suppress the Serbian identity" of the province and describing its preamble as "characteristic of a constitution of an independent state.

"[19] The following year, he opposed an anti-discrimination bill that offered protection to LGBTQ citizens, charging that it amounted to a "persecution of Christians.

[21] In late 2009, he travelled to the Netherlands for his first meeting with SRS leader Vojislav Šešelj, who was then facing war crimes charges at the International Criminal Tribunal for the Former Yugoslavia (ICTY) in The Hague.

In an interview prior to the meeting, Martinović acknowledged that he had risen to a leading role in the party in a short period of time.

[24] Serbia's electoral system was reformed in 2011, such that all parliamentary mandates were awarded to candidates on successful lists in numerical order.

[26] The party's local leadership in Serbia also sought to nominate Martinović in the concurrent presidential election, but Šešelj overrode their decision and selected his largely apolitical wife Jadranka for the role.

[40] He endorsed Ana Brnabić as Serbia's new prime minister in June 2017, saying that she would continue a path of integration with the European Union while also seeking stronger connections with Russia and China.

"[42] Martinović and fellow SNS parliamentarian Sandra Božić went on a two-day hunger strike in May 2020 to protest what they described as the inaction of Serbia's prosecution and judiciary against the violent behaviour of Dveri leader Boško Obradović.

[50] Martinović later apologized, saying, "I did not intend to offend the citizens of the Republic of Serbia who do not or cannot have children, and I believe that my speech was interpreted in a completely wrong way.

[52] He rejected accusations of discrimination against Albanians in Serbia later in the year, saying his ministry was applying the law in an equal manner to all citizens.

[57] In August 2024, Martinović said that Rio Tinto's proposed mining of jadarite in Gornje Nedeljice would not pose a problem for agriculture, citing a study produced by his ministry.