LIMA (Reuters) - Hundreds of protesters supporting and opposing Peruvian President Pedro Castillo congregated around Congress in capital Lima ahead of a vote on Tuesday on whether to impeach the under-fire leftist president.

       Peruvian lawmakers will vote on whether to begin impeachment proceeding for "moral incapacity," though the chances appear slim of ousting Castillo, who has been battling crises as his popularity wanes months into his administration.

       Castillo's own party, the Marxist Peru Libre, had at one point considered supporting the motion, though on Monday rallied behind the president despite clashing with him over policy and called the attempt a right-wing coup.

       "We want him to keep working," said María Lázaro Cornelio, a protester supporting Castillo, a former school teacher who came to office in July pledging major social change. "We want him to keep his word on things that he has promised us."

       Another protester, who gave her name as Jacky, said she wanted Castillo out because she alleged he was "destroying Peru, destroying our economy and the freedom of all Peruvians."

       The impeachment push, backed by right-wing lawmaker and defeated presidential candidate Keiko Fujimori, has appeared to lose steam in recent days after Castillo held talks with various political parties earlier this week.

       "The issue of vacancies is slowly being deflated," Vice President Dina Boluarte told reporters on Tuesday.

       The three right-wing parties seeking Castillo's removal have 43 legislators. The motion would need 52 votes from the 130 members of Congress to move forward and then 87 votes in a later vote to remove the president from office.

       The debate in Congress comes as prosecutors investigate alleged cases of corruption by aides to Castillo, who has accused his opponents and "economic interest groups" of conspiring against him.

       The Andean country's fragmented Congress has a history of clashing with the executive branch.

       The copper-rich country has had five presidents since 2016. In 2018, Pedro Pablo Kuczynski resigned from the presidency minutes before an impeachment vote, while centrist Martín Vizcarra was ousted following two impeachment trials last year.

       (Reporting by Marco Aquino; Editing by Adam Jourdan and Sandra Maler)