Peru's president has offered his resignation to Congress after videos surfaced in which several of his allies were filmed allegedly trying to gain the support of a lawmaker in a vote on the leader's impeachment.

Pedro Pablo Kuczynski, 79, made the announcement in a televised address to the nation on Wednesday, a day before he was due to face an impeachment vote over corruption allegations.

Kuczynski promised an orderly and constitutional transition of power.

"I don't want to be an obstacle for the nation finding the path of union and harmony that it so badly needs and which was denied to me," he said.

It was not immediately clear if Congress would accept the resignation.

On Tuesday, videos emerged apparently showing some of the president's backers allegedly trying to buy the support of a lawmaker so he would block Kuczynski's impeachment.

The former Wall Street investor had been accused of covering up decades-old illegal payments from Brazilian construction giant Odebrecht.

The company became embroiled in a political scandal after admitting to paying more than $788m in bribes to win construction contracts across 12 countries, including Argentina, Mexico and Venezuela.

The accusations centre on Westfield Capital Ltd, a company owned by Kuczynski, which received $782,000 from Odebrecht, according to Peruvian national paper El Comercio.

Kuczynski has denied any wrongdoing.

Reporting from the capital Lima, Al Jazeera's Mariana Sanchez said if Congress accepts the president's resignation, Kuczynski could face criminal proceedings.

"Constitutional lawyers say that the president, who has immunity for a period of time of five years after he leaves the presidency, would only have immunity for crimes committed during his presidency.

"The crimes that he allegedly committed when he was a finance minister more than a decade ago happened way before his presidency, so constitutional lawyers say that he could be taken to trial very soon and that he does not have immunity for that," she said.