SEOUL, South Korea >> Hundreds of thousands of South Koreans are expected to march in capital Seoul for the sixth straight Saturday calling for the removal of scandal-plagued President Park Geun-hye, who faces an impeachment vote in parliament next week.

The demonstration will come hours after lawmakers formally launched an attempt to impeach Park. State prosecutors accuse her of helping a close confidante extort money and favors from large companies and manipulate state affairs.

Police say the turnout in streets near the presidential office could be similar to what was the largest anti-Park protest last Saturday when they sized the crowd at 270,000. Protest organizers estimated the crowd at 1.5 million.

Thousands were also expected to rally near the National Assembly to pressure parties, including Park’s conservative ruling party, to vote for her impeachment.

Opposition parties controlling South Korea’s parliament waited until after the end of this week’s plenary session to register an impeachment motion early Saturday. It means the vote will take place next Friday.

The motion, which had the support of 171 opposition and independent lawmakers, accuses Park of violating the constitution and undermining democracy by allowing her longtime friend, Choi Soon-sil, to interfere in state affairs, and letting senior presidential aides help Choi extort from companies.

It also accuses Park of committing other crimes, such as abuse of authority, coercion and bribery, over allegations that large companies were bullied or offered rewards for giving money and favors to foundations and businesses Choi controlled.

“President Park Geun-hye, in executing her duty, has broadly and seriously violated the constitution and laws,” the impeachment motion says.

The opposition had earlier planned to call for a vote this week, but it squabbled over timing after Park made a conditional offer to resign.

The opposition lacks votes to push through with Park’s impeachment without help from dissenters in the ruling party.

A group of anti-Park lawmakers in the ruling party have vowed to vote for her impeachment if she fails to announce by Wednesday that she will step down voluntarily in April.

On Tuesday, Park, without providing a timeline, said she would leave office if parliament comes up with a stable power transfer plan. Opposition lawmakers criticized the overture, saying it was a stalling ploy aimed at luring back members of her party who supported impeachment.