Both men are among 23 candidates running for president. One independent candidate and a member from a party linked to Mugabe also won one seat each.
At least 4 people were shot dead by Zimbabwe military as tension rises over election results.
Defeat for the ruling party would likely lead "to a denunciation of the election by the Mnangagwa administration and the potential for the military to intervene to secure power for ZANU-PF", the London-based BMI risk consultancy said.
He added: "The presence of the army is not to intimidate people but to ensure that law and order is maintained". They will remain under police command, the spokeswoman, Charity Charamba said.
Parliamentary results show Zanu-PF heading for a big majority. There has been no announcement on the presidential vote.
Zanu PF United Kingdom branch chairperson, Nick Mangwana has already congratulated his party Zanu PF for attaining majority of National Assembly seats, with 72 % of declared by the ZEC.
Zimbabwe's main opposition has said Mr Chamisa won the presidential election, sparking street celebrations by supporters on Tuesday. While ZANU PF won heavily in the rural areas.
The MDC accused the election commission yesterday of deliberately delaying results of this week's vote to favour the ruling party, reporting irregularities in the first poll since the removal of Robert Mugabe in a bloodless November coup.
The opposition supporters had gathered outside the compound of the electoral commission and were met by riot police who fired tear gas.
"I was making a peaceful protest. I was beaten by soldiers", Norest Kemvo, who had gashes to his face and right hand.
"This is our government".
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They were assisted by fire-retardant drops from air tankers and a decrease in wind conditions in the area on Friday. The Carr Fire is one of 88 burning nationally, mostly across the American west.
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The Observatory said government forces battled jihadists who stormed the villages from an IS pocket northeast of the city. The province's governor, Amer al-Eshi, told state-run Ikhbariyah TV that Sweida had been secured by Wednesday afternoon.
The crowds chanted: "We want Chamisa". "They are stealing our election".
"The results are biased, trying to give the impression that ZANU has won", said Lawrence Maguranyi, 21, an MDC supporter and university student. Why are the army here beating us? shooting us?
This is the first time in 16 years that the government has allowed European Union and U.S. election monitors into the country.
Zimbabwe holds parliamentary and presidential elections separately, with the electoral commission saying the outcome of the latter will be released "sometime tomorrow".
The EU did not understand why the release of the presidential result was taking so long, Brok said.
Zimbabweans desperately hope the peaceful vote will lift them out of economic and political stagnation after decades of Mugabe's rule, but the country is haunted by a history of electoral violence and manipulation that means trust is scarce.
Opposition leader Nelson Chamisa has accused the ruling ZANU-PF party of trying to steal the election.
The bloc will deliver a preliminary report on the conduct of the election on Wednesday, as will the Southern African Development Community (SADC) and the African Union teams.
Augusto says efforts should be made to allow the millions in Zimbabwe's diaspora, barred from voting overseas, to vote in future elections.
The commission had earlier warned that the results of the presidential first round may not be known until Friday or even Saturday and would not be released until tallies were received from all 10,985 polling stations.
The EU observer mission said "a truly level playing field was not achieved" in the election, pointing out the "misuse of state resources, instances of coercion and intimidation, partisan behaviour by traditional leaders and overt bias in state media".