Montenegrin Prime Minister Milo Djukanovic on December 28 called for a vote of confidence in his government, following weeks of protests over his move toward joining NATO.
"Questions have been raised as to whether this government enjoys the support of parliament," Djukanovic told reporters in Podgorica, stressing that he believes joining the Western military alliance is in the country's best interests.
In recent months, the opposition has called for Djukanovic's resignation and riot police in the capital Podgorica have clashed with thousands of protesters demanding elections.
If the premier does not secure the support of parliament in a vote planned for early 2016, he would have to call legislative elections and would stay in the job until a new government is formed.
Djukanovic has led the tiny Balkan nation of 650,000 as president or premier since 1991.
Montenegro received an invitation from NATO to join on December 2.
Montenegro gained independence from Serbia in 2006, but has a strong Serbian community that is traditionally allied with Russia and, like Moscow, bitterly opposes any move to join NATO.