Spokane County Sheriff, File, Associated Press
FILE - This undated file photo provided by the Spokane County Sheriff shows Bombing suspect Kevin William Harpham. Harpham, who has extensive ties to white supremacists, will be sentenced Tuesday, Dec. 20, 2011 after pleading guilty to federal charges he planted a bomb intended to hurl poison-laced shrapnel into marchers at a Martin Luther King Jr. Day parade in Spokane last January.

SPOKANE, Washington — The attorney for a man with extensive ties to white supremacists asked a judge Tuesday to withdraw his client's guilty plea in connection with a plan to detonate a bomb at a Martin Luther King Jr. Day parade.

The request by Kevin Harpham's defense team came just hours before he was scheduled to be sentenced in Washington state. Harpham previously agreed to a plea deal charging him with attempted use of a weapon of mass destruction, and the hate crime of placing the bomb in an effort to target minorities.

He faces 27 to 32 years in prison.

Harpham told a judge in September that he placed a pipe bomb loaded with poison-laced metal along the parade route in Spokane as an attempt to commit a hate crime.

The Jan. 17 parade drew about 2,000 and was forced onto an alternate route after the bomb was found.

Harpham is an Army veteran who has extensive ties to white supremacist groups but no record of past crimes.

The Southern Poverty Law Center, which tracks hate groups, has said Harpham made more than 1,000 postings on a white supremacist website. The center also has said Harpham belonged to a neo-Nazi group.