As vote counting continues, here are five things to know about the elections in the East African nation.
And experts say that's unlikely to change.
Museveni, 71, has been in office since his rebel group seized power in 1986. In 2005, the constitution underwent changes to allow him to extend his term.
As he tries to maintain his grip on power, experts emphasized the difficulty of unseating incumbents on the African continent.
"A re-election for Museveni would signal the persistent advantages incumbents have in controlling the political process, making it very difficult for opposition parties or candidates to compete with national structures, finance and support from partisan government institutions," said Magnus Taylor, an analyst at the International Crisis Group.
African leaders have come under fire for extending term limits. Rwanda amended its constitution to allow its leader to potentially rule until 2034. In nearby Burundi, the President's decision to change the constitution to run for a third term last year sparked violence that left more than 300 people dead.
2. Uganda is a major U.S. ally
The United States' diplomatic relations with Uganda date back to 1962, when the nation gained independence from Britain.
Since taking over, Museveni has been credited with keeping Uganda safe despite terror strikes in nearby nations.
Al-Shabaab attacked the capital, Kampala, six years ago
, but the nation has remained relatively free of terrorism despite sending troops to fight the militants in neighboring Somalia. Its neighbor, Kenya, has been been under constant attacks by the terror group since it sent troops to Somalia.
The U.S. considers Uganda an ally in regional security
, especially because its troops are a key part of the African Union forces battling the extremists in Somalia.
3. Incumbent, competitor have complicated past
Opposition leader Kizza Besigye, 59, is the incumbent's closest competitor and one of eight candidates running for president this year.
He is also Museveni's former doctor who served as a minister in his Cabinet.
This is not Besigye's first attempt to unseat his former boss. He lost presidential bids in 2001, 2006 and 2011.
Since cutting ties with his former patient, Besigye has had a rocky relationship with the government, which he describes as authoritarian.
He has been arrested numerous times, especially during the campaign season. On Thursday -- election day -- he was detained after he tried to enter a facility he said had illegal election materials, police said.
He was being detained at his home Friday as one of six opposition officials held under "preventative arrest," police spokesman Patrick Onyango said.
The officials were detained because they were heading to announce election results tallied by the opposition and not election officials, Onyango said.
"They are not mandated under any law to announce results," Onyango said.
Meanwhile, the Red Cross said two people died following violence at the offices of the opposition party, which had been besieged by police and military forces.
4. President banned social media
On top of Besigye's arrest, tensions mounted over a spontaneous ban on social media
and allegations of voter fraud. On Thursday, the government stopped voters from tweeting or updating their Facebook pages.
Incumbent Museveni defended the ban as a "security measure to avert lies" during the election.
But many citizens used encrypted private networks to circumvent the ban. Maybe they learned from the past. A similar shutdown occurred during the 2011 general election.
Human rights groups condemned the clampdown.
"Without clearly defined security concerns, this closure is nothing but an exercise in censorship as Ugandans elect their leaders," said Sarah Jackson, Amnesty International's deputy regional director.
5. Social media played a key role in election
Throughout the election, social media has been a rallying and debate tool.
In January, Ugandans used the hashtag #1986pictures
with tweets of old pictures and remarks such as "In 30 years, everything has changed in Uganda except the President."
Rights groups have warned that freedom is under threat.
"Uganda has seen increased levels of authoritarianism in the last decade," said Magnus Taylor, Horn of Africa analyst at the International Crisis Group. "This has come in waves, most evident during election period when a generally strident opposition has clashed against the President's anti-democratic tendencies."