ABC' News' Jonathan Karl reports: The Senate was expected to vote on the Dodd-Frank Financial Reform bill this week, giving the President the opportunity to sign the most sweeping overhaul of Wall Street regulations since the Great Depression before Congress's July 4 recess. But … Without Robert Byrd — or a Democratic replacement to fill Byrd's seat — they may not have the votes to pass it. On the critical procedural vote that enabled the bill to pass the Senate on May 20, Democrats prevailed 60-40. Senator Byrd's vote was essential; the bill had exactly the number of votes needed to pass. And there's this: Democrats seem to have lost another vote. Sen. Scott Brown, one of just four Republicans in the Senate who voted for the Senate's version of the bill, is now suggesting he may oppose it because it now includes $18 billion in taxes and fees. "While I'm still reviewing the bill's details," Brown said on Friday, "my fear is that these costs would be passed onto consumers in the form of higher bank, ATM and credit card fees and put a strain on lending at the worst possible time for our economy. I've said repeatedly that I cannot support any bill that raises taxes." Democratic Senators Maria Cantwell and Russ Feingold voted "no" on the Senate bill because they believe it is not tough enough on Wall Street. With Brown now in the "no" column, there will be renewed pressure on both of them to change their votes to "yes." Further complicating matters is the position of Sen. Chuck Grassley, the Iowa Republican, who voted against the procedural vote that allowed the Wall Street reform bill to pass. He argued that Democrats should have allowed more debate. Grassley then voted in favor of final passage. If Grassley votes in favor of proceeding to the Wall Street reform conference report, it could nullify Democrats' need for Brown to stay with them. Stay tuned.