The Egyptian Popular Current has criticised the army's backing for a presidential bid by army chief Abdel-Fattah El-Sisi.
The Current, founded by Nasserist politician and former presidential candidate Hamdeen Sabbahi, expressed "surprise" at the army's statement, which reflects, in the current's view, "clear interference in the upcoming presidential polls and Egypt's future political arrangements."
Such "interference" is at odds with the Current's outlook on the constitution and democracy, it said.
In a statement on Monday the Supreme Council of the Armed Forces (SCAF) said El-Sisi had "a mandate and an obligation" to run for president and empowered him to become a candidate.
The SCAF's statement entrenches the impression that El-Sisi is the army's candidate, which kills the spirit of real political competition and the people's right to choose their president, the Current said.
The military should not discuss the future political role of a serving soldier because it is prohibited from engaging in politics, the Current said.
The army's statement was particularly unwarranted, the Current added, because it did not actually confirm whether El-Sisi would stand for president.
The Current said its complaint stemmed from its concern for the military's integrity, which had aligned itself with the popular will in February 2011 and July 2013, when presidents Hosni Mubarak and Mohamed Morsi were ousted.
"The army's backing of a particular presidential candidate moves it from a position of national consensus and high standing to a place where it may be subject to disputes as it becomes a player in the political process," the statement said.
El-Sisi should continue as defence minister to guarantee the country's safety and its revolution, it added.
Hamdeen Sabbahi said in December that he would prefer El-Sisi to remain in the army, but also that he would respect political forces if they wanted the army chief to stand for president.
Sabbahi, who came third in last year's presidential poll, has said he will stand again in elections expected in the spring of 2014.
The Popular Current has already launched a campaign to promote Sabbahi as the "revolution's candidate."
Parliamentary and presidential elections are expected to take place by summer 2014, as detailed by the post-Morsi roadmap.