SUDBURY, Ont. - Ontario Premier Kathleen Wynne is to testify today in a bribery trial involving a former top adviser and a Liberal fundraiser.

Pat Sorbara, Wynne's former deputy chief of staff and Liberal campaign director, and Gerry Lougheed, a local Liberal organizer, are charged under the Election Act.

Both have pleaded not guilty at the trial in Sudbury, Ont., to offering would-be candidate Andrew Olivier a job or appointment to get him to step aside for Wynne's preferred candidate in a 2015 byelection in the city.

That preferred candidate was then-New Democrat M-P Glenn Thibeault, who ended up winning that byelection for the provincial Liberals and is now energy minister.

Thibeault has previously denied he sought anything that would be seen as a bribe in exchange for running and is not charged with any offences.

Wynne faces no charges, but will be likely asked to testify about what she told Olivier and what conversations she had with Lougheed and Sorbara prior to their conversations with him.