Soft money's evolution a study in politics.

What is soft money?

It's those six- and seven-figure contributions from corporations, rich people, labor unions and interest groups that both parties rake in despite long-standing restrictions on the size and source of campaign donations.

It pays for many of the television ads you see before an election.

It comes in amounts that far exceed the $1,000 legal limit on the check that you could write to a campaign for president or Congress. It comes despite a ban on corporate giving that dates to Teddy Roosevelt's time.

When Democrat Bill Bradley and Republican John McCain shook hands in New Hampshire Thursday and pledged to spurn soft money if their parties nominate them for president, they will be calling into question a powerful …