Business groups are reacting with frustration and caution to the somewhat chaotic and piecemeal way in which Congress is handling jobs legislation. And the rancorous debate over the bills may be straining relations between some Republican Members and their traditional downtown allies.

The procedural roadblock thrown up by Republican Sen. Jim Bunning (Ky.) that had prevented the extension of highway funding and unemployment benefits has dismayed many lobbying groups.

And lobbyists complain that Republican lawmakers have been reluctant to back amendments sought by various industries.

Even though they have prodded Congress to find ways to boost economic growth, many of the major trade groups have mixed views of the package of bills now moving haltingly on Capitol Hill.

They support the extension of tax credits in areas such as research and development, but are less enthusiastic about a provision to encourage small business to hire new workers.

The uncertainty over what may end up in the final legislation and ambivalence over what has already been approved has prompted business groups to take a pass so far on scoring lawmakers in how they vote on these bills. The ratings of lawmakers on “key votes” by business groups has traditionally been a significant factor during election years. Republicans, in particular, have sought the support of business groups.

However, officials from three major business organizations — the U.S. Chamber of Commerce, the National Federation of Independent Business, and the National Association of Manufacturers — said they did not score the jobs bill that was approved by the Senate last week. In that vote, five Republicans, including newly elected Massachusetts Sen. Scott Brown, broke with the rest of their party to support cloture.

The bill would suspend Social Security payroll taxes for small businesses that hire the unemployed. However, an NFIB spokeswoman said the group believes a broader “payroll tax holiday” that wouldn’t be specifically tied to hiring new employees would be more effective.

“There won’t be a key vote on this. There is not a whole lot in there for small business,” said the NFIB’s Melissa Sharp. She added that her group had not decided whether it will score another bill that is now being considered by the Senate that includes the tax extenders.

“We’re waiting to see how it all unfolds,” she said. “We want to see what amendments there will be.”

NAM is pursuing a similar approach.

“We’re taking it one day at a time. It is not black and white for us,” NAM spokeswoman Erin Streeter said.

Last month, NAM President John Engler issued a statement expressing disappointment after Senate Majority Leader Harry Reid (D-Nev.) decided to split up a comprehensive jobs bill that had been brokered by leading Republicans and Democrats.

That original bill included tax extenders provisions as well as tax incentives for small-business job creation and extensions of unemployment and health benefits. However, some liberal Democrats were angry that the bill extended tax incentives for the year while it only continued unemployment benefits for three months.

The tax extenders include not only research and development credits, but biofuel production incentives, breaks for people affected by natural disasters, investment in economically hard-hit areas and favorable tax treatment of farm equipment. The tax extenders were included in a larger bill approved by the House late last year.

Even though his group supports the tax extenders, Ralph Hellmann, senior vice president of the Information Technology Industry Council, said that it will not score lawmakers on the bill because it contains nothing new.

“It doesn’t merit a key vote,” he said.

While Reid has said that Senators can offer amendments to the tax extender bill, there has been concern on K Street that Republicans are not interested in helping Democrats pass the legislation.

One business lobbyist said that Republican Senators were refusing to agree to vote for amendments sought by certain industries. The lobbyist said that K Street “wants to get stuff done” but that “these traditional allies won’t commit.” The lobbyist added that Reid was reluctant to support amendments without assurances that Republicans would back it as well.

One provision in the jobs package, the extension of the highway bill, has the support of a wide range of industry groups from the chamber to transportation trade groups.

The lobbyists for these groups have been aghast at the procedural maneuvers that delayed the Senate from voting on the measure, which includes highway spending as well as extension of unemployment and health benefits.

“It is embarrassing,” said Jeff Solsby, a spokesman for the American Road & Transportation Builders Association.

Solsby said that his organization doesn’t have key votes on the issue but has been urging its members from around the country to call their lawmakers. The Department of Transportation has already furloughed employees, and a number of projects nationwide are threatened because the highway funding expired at the end of February.

Charles Lovorn, the executive director of the Kentucky Association of Highway Contractors, expressed exasperation with his home-state Senator.

“We’ve asked our friends in other states not to hold it against us,” Lovorn said, adding that his group has been in conversations with Bunning’s staff about the need for highway construction. He also said that representatives from large highway engineering consulting firms had met with Bunning’s staff.

But Lovorn had given up on Bunning.

“You can’t impeach him,” he said. “You’re talking about a Senator who is not running for re-election. He doesn’t have any thoughts about what this does for his own party.”

Bunning has defended his action, arguing that there should be offsets to pay for the increased spending in the jobs bill. But Tuesday evening he relented and an agreement was reached.

Another group that has been angry at the delays is the American Medical Association. Among the provisions being held up is one that would delay a scheduled 21 percent reduction in Medicare payments to physicians.

Doctors from around the country have converged on Washington this week to lobby lawmakers on the Medicare issue and other health care legislation.

AMA President J. James Rohack wrote on his blog posted on the organization’s Web site Tuesday that the Senate does not grasp how it has made the Medicare reimbursement situation worse by its inability to act.

“But as the House of Lords, the Senate at times becomes like Marie Antoinette with her reply of ‘let them eat cake’ when the common person was faced with starvation,” Rohack wrote.