How difficult is it in the U.S. to challenge a grand jury bill of indictment?

Factual Questions
1

Remember the two yahoos who were picked up last fall on charges of wanting to go on a white supremacist murder rampage of blacks, culminating in a suicide attack on Barack Obama while wearing white tuxedos?

They’ve been indicted by a federal grand jury, but their lawyers are challenging the indictment, on two different grounds: that the racial composition was unbalanced (too many black folks, not enough white folks), and that the individual members of the grand jury were not impartial.

See this recent article: Lawyers for men accused in Obama plot seek more time.

My question: how likley is it that either of these challenges will succeed? Is it very difficult to challenge a grand jury’s decision in the U.S. system? (We no longer have grand juries in Canada, so all I know about them is what I’ve seen Jack McCoy do :dubious: )

2

Assuming these are federal charges- which they seem to be- not that hard, although I can’t find number on the success rate of motions to set aside or dismiss an indictment.

The irony of white suspects complaining about a jury with too many black people on it is delicious.

Also, the first guy looks like Sinead O’Connor.