President Tayyip Erdogan, whose ruling party's alliance has a majority but faces opposition to the plan in parliament, said last week Turkey would deploy troops in Libya to support Fayez al-Serraj's internationally-recognized Government of National Accord (GNA).
The GNA has requested Turkish support as it fights off an offensive by General Khalifa Haftar's forces in the country's east that is backed by Russia, Egypt, the United Arab Emirates (UAE) and Jordan.
Analysts and officials say Ankara is unlikely to immediately send troops, but rather military advisers and equipment.
A senior Turkish official said last week Turkey may train Libyan soldiers in Turkey, and Reuters reported that Ankara is also considering sending allied Syrian fighters to Tripoli as part of the planned military support.
On Wednesday, Vice President Fuat Oktay said the bill served a symbolic role that Ankara hoped would be a "deterrent" to the parties, and that Turkey may not send troops if Haftar's forces halted their offensive and pulled back.
"The deployment will likely start with military advisers, increased (drones), and special operations that would work with the Libyan military," said Sinan Ulgen, a former Turkish diplomat who is chairman of the think-tank Center for Economics and Foreign Policy Studies.
"The hope would be that the Turkish military may not itself be involved in military action," he said.
Erdogan's ruling AK Party and its nationalist allies are expected to back the legislation on Thursday despite opposition from the other major parties that say military support would cause Libya's conflict to spread across the region and endanger Turkey's safety.
Ankara signed a military cooperation accord with Tripoli in November and has said it would help prevent Libya sliding into "chaos." It is also meant to protect Turkish private investment in Libya and bolster Turkey's offshore energy claims in the Mediterranean.
But it could also put Turkey at odds with the other foreign players in Libya's war and in the region. The Arab League is the latest to warn against the deployment of foreign fighters in the North African country.
"Ankara sees its involvement in Libya as a symbol of its new status as a regional power," said Asli Aydintasbas, senior policy fellow at the European Council on Foreign Relations. "The idea is, to be at the big table, you need to be present on the ground."
Ankara has already sent military supplies to the GNA despite a United Nations arms embargo, according to a U.N. report seen by Reuters.
Better drones from Turkey could help the GNA.The U.N. said Haftar's Chinese-made drones, which were provided by the UAE and have a broad range, flew 800 air strikes until November, while the GNA's Turkish-made drones carried out 200.