Should Federal Contractors Disclose Campaign Contributions?

What's your view on this?:

Opposition Grows to White House Executive Order on Contractors, by Danny Yadron: Opposition to a White House proposal to require federal contractors to disclose all campaign contributions intensified on Thursday as Republicans – and some Democrats – said it would skew the government’s bidding process.

Two House committees prepared Thursday afternoon to hold a joint hearing on the topic... And four senators sent a letter to the White House critiquing the draft executive order, which the White House is still mulling.

“The requirement that businesses disclose political expenditures as part of the offer process creates the appearance that this type of information could become a factor in the award of federal contracts,” the lawmakers wrote. Sens. Claire McCaskill (D., Mo.), Joseph Lieberman (I., Conn.), Susan Collins (R., Maine) and Rob Portman (R., Ohio) signed the letter.

The draft order would require any firm seeking a federal contract to disclose all political spending of more than $5,000 for the previous two years. Such spending is already included on monthly and quarterly campaign finance reports, but the executive order would create a central database on the executive branch website data.gov. It would also require disclosures of donations to groups that do not have to disclose their donors, such as Crossroads GPS and the U.S. Chamber of Commerce. ... Democratic leader Nancy Pelosi said Thursday she agreed with the White House, noting it would bring more transparency to federal spending. ...

I don't get the argument that Lieberman and others are making that this "creates the appearance that this type of information could become a factor in the award of federal contracts." It's the suspicion that such donations are already making a difference that is motivating the request for more light on this activity. I can't see the harm in this beyond a general concern for privacy (an important consideration). But I'm partly using the rule that if Lieberman is for it, it must be wrong -- a rule that has served me well in the past -- so perhaps I'm missing good reasons to oppoe this policy? Is this a good or a bad idea?