Former President Levon Ter-Petrossian has claimed that he is the rightful first-round winner of the February 19 ballot, which he alleges was tainted by widespread fraud, intimidation, and violence.
Official results released by the Central Election Commission show that Sarkisian, who received vocal support from outgoing President Robert Kocharian, won nearly 53 percent (52.78) of the vote. Ter-Petrossian, who served as Armenia's first post-Soviet president before being forced to resign in 1994, received 21.5 percent.
But on February 21, two members of the Central Election Commission representing opposition parties refused to endorse the official results, according to RFE/RL's Armenian Service.
And on February 22, the opposition's stance was bolstered with the resignation of a deputy parliament speaker and support offered by a deputy prosecutor-general.
The resignation of deputy parliament speaker Vahan Hovannisian came as a surprise, as he was considered to be relatively close to the government. He ran in the February 19 election as a candidate for the Armenian Revolutionary Federation-Dashnaktsutiun.
Explaining his disappointment in the way in which the elections were carried out, Hovannisian said, "I made my personal decision and decided to resign."
Deputy Prosecutor-General Gagik Jahangirian also joined the fray, telling cheering demonstrators that, while he had seen many elections in Armenia, he had "never seen the level of violations and violence as this time."
He told RFE/RL on February 22 that votes must be defended. "If you do not defend your vote today, do not complain tomorrow about the illegal intimidation, illegal court decisions or imprisonment," Jahangirian said. "You will have the right to complain only about yourself."
In a later interview, Prosecutor-General Aghvan Hovsepian's spokeswoman Sona Truzian requested that President Kocharian dismiss Jahangirian over his involvement in politics.
The authorities have said that law enforcement bodies will be sent in to quell any violence or illegal actions in the course of the protests. But Ter-Petrossian has said the protests will remain peaceful. After the February 21 rallies, some supporters began pitching tents on Liberty Square, where the unsanctioned rallies are being held.
Ter-Petrossian told his supporters the same day that two prominent generals with high-ranking posts in the Defense Ministry had assured him that they would not permit the army to be deployed against them.
The claim that Deputy Defense Ministers Manvel Grigorian and Gallik Melkonian had made such promises has been denied by the Defense Ministry.
But Miasnik Malkhasian, deputy chairman of the influential war veterans union Yerkrapah, dismissed the Defense Ministry's statement in an interview with RFE/RL.
"If Manvel Grigorian himself does not deny in any way that he has joined Levon Ter-Petrossian's team -- does [Defense Ministry spokesman] Seyran Shahsuvarian have the right to deny it?" he said.
In its preliminary assessment, the Organization for Security and Cooperation in Europe's election-monitoring body said the vote was "mostly in line with the country's international commitments, although further improvements are necessary."
The vote-counting process was assessed negatively at about 16 percent of the polling stations visited by the organization's mission observers.
U.S. State Department spokesman Edgar Vasquez on February 20 expressed concern over the description of the vote count as bad or very bad at those stations, RFE/RL's Armenian Service reported.
Sarkisian has received messages of congratulation on his election win from the presidents of Russia, France, Georgia, and Turkey.
(RFE/RL's Armenian Service contributed to this report.)