US president-elect Barack Obama's smooth transition process hit a snag less than a week before his historic swearing-in as questions over his choice for treasury secretary delayed the confirmation hearing for that key post.

Obama's pick for attorney general was also expected to face aggressive questioning yesterday, as it became apparent that not all Cabinet choices would earn quick approval from Congress.

The transition hit an embarrassing bump on Tuesday when Treasury Secretary-designate Timothy Geithner owned up in a closed-door session with senators to failing to pay $34,000 in taxes from 2001 to 2004. The oversight has been corrected, but Senators on Wednesday pushed back his confirmation hearings by at least a week.