US vice presidential candidate Sarah Palin will make a formal legal statement about allegations that she abused her powers as Governor of Alaska.
A separate inquiry, dubbed 'Troopergate' by the US media, has already found that she acted unethically, but not illegally, when she dismissed a senior official last summer.
Governor Palin will give a deposition for a second investigation into allegations that she tried to have her brother-in-law, an Alaskan state trooper, fired.
The ongoing controversy has been partly blamed for a continuing decline in opinion polls for Republican US presidential candidate John McCain.
A growing number of conservative commentators have described his choice of vice-president as unprepared for office.
The US media has also criticised her self-styled 'hockey mom' image following the revelation that $150,000 of McCain campaign funds were used to buy clothes for herself and her husband.
