Jacquelyn Martin/Associated Press, Andrew Harrer/Bloomberg News

Government regulators on the Wall Street beat have long been outnumbered and outspent by the companies they are supposed to police. But even after receiving budget increases from Congress last month, regulators are still falling behind.

The Securities and Exchange Commission and the Commodity Futures Trading Commission are struggling to fill crucial jobs, enforce new rules, upgrade market surveillance technology and pay for travel.

On a recent trip to New York to tour a trading floor, a group of employees from the commodities watchdog rode Mega Bus both ways, arriving late to their meeting despite a 5:30 a.m. departure. The bus, which cost $30 a person round trip, saved the agency roughly $1,000 over Amtrak.

“We spent hundreds of billions of dollars on a hideous bailout, and now we’re not going to fund reforms to prevent another one,” said Bart Chilton, a commissioner with the agency.

The money squeeze comes as Wall Street regulators take on added responsibilities in the wake of the financial crisis, including monitoring hedge funds, overseeing the $600 trillion derivatives market and other tasks mandated by the Dodd-Frank law.

Their budgets may soon be even tighter, with Republicans looking to cut the regulators’ spending beginning Oct. 1, the start of the government’s fiscal year. Gary Gensler, the chairman of the commodities agency, and Mary L. Schapiro, the head of the S.E.C., will discuss their budgets for the 2012 fiscal year before a Senate committee on Wednesday.

Current and former regulators warn that budgets cuts would prevent the agencies from enforcing hundreds of new rules enacted under Dodd-Frank, or worse, catching the next Bernard L. Madoff.

But critics contend that the agencies don’t deserve extra money, given that they missed warning signs and failed to catch serious wrongdoing in the years leading up to the crisis. The S.E.C., too, has been accused of mismanaging its finances. The Government Accountability Office has faulted the agency’s accounting almost every year since it began producing financial statements in 2004.

Some Republicans argue that the regulators’ cries of poverty are overblown. The S.E.C.’s budget this year is $1.18 billion, up 6 percent over 2010 — and nearly triple what it was a decade ago.

“A dramatic spending increase to fund the S.E.C. and C.F.T.C., as envisioned by the authors of the Dodd-Frank legislation, would further the mind-set that our nation’s problems can be solved with more spending, not more efficiency,” Representative Scott Garrett, the New Jersey Republican who leads the House Financial Services Committee’s Capital Markets panel, said in a statement earlier this year.

While hiring bans and travel restrictions have been eased since the new budget, regulators say they are largely in a holding pattern as lawmakers debate the 2012 budget. Any further cuts, they say, could undermine their efforts to police Wall Street.

The commodities agency says the uncertainty has forced it to delay some investigations and forgo other potential cases altogether.

“We don’t have the sufficient number of bodies to pursue all relevant investigations and leads,” said Mr. Gensler, adding that his agency was short nearly 70 people in its enforcement division.

Robert S. Khuzami, the S.E.C.’s enforcement chief, has similar worries, noting that some Wall Street investigations have faced mounting delays. Recent departures of lawyers will only magnify the problem, he added.

Mr. Khuzami also said he faced a “significant backlog” of tips and referrals, including in the area of market manipulations and accounting irregularities. The tips, which come from whistle-blowers, law enforcement agencies and investors, often prompt S.E.C. investigations.

“The biggest concern is we’re not going to get to fraud and wrongdoing as early as we should,” he said. And if the agency’s budget is not increased in 2012, the S.E.C.’s enforcement division “won’t cast as wide a net,” he added.

Already, the S.E.C.’s enforcement division has adopted cutbacks. The division, for instance, has curbed its use of expert witnesses in some securities fraud trials, Mr. Khuzami said.

The division also started sending only one lawyer — sometimes a junior staff member — to conduct depositions and interview witnesses, according to defense lawyers and people close to the agency. Senior S.E.C. lawyers monitor the depositions via videoconference.

To avoid hotel costs, some S.E.C. investigators have shuttled between New York and Washington on Amtrak trains that leave around dawn and return the same day. The agency only recently started to again examine investment firms and public companies in some Southern states, after postponing reviews to avoid paying for plane fares.

Despite the recent budget increase, the S.E.C. “still must closely monitor expenses such as travel to make sure that each expense is truly mission-critical,” according to an internal agency memo dated April 14 that was provided to The New York Times. “It is not at all clear what fiscal year 2012 funding level will be approved by Congress,” said the memo, which was signed by Jeff Heslop, the S.E.C.’s chief operating officer.

While the S.E.C. offsets its budget with fees from Wall Street banks and other financial firms — and in recent years has even turned a profit for taxpayers — Congress sets the agency’s spending levels each year. Lawmakers in April raised the S.E.C.’s budget for the next few months by $74 million, to $1.18 billion. President Obama had requested $1.25 billion for the agency, and Dodd-Frank called for $1.3 billion.

The Commodity Futures Trading Commission received $202 million. Although that was a 20 percent increase over the previous year, the budget fell short of the $261 million the agency said it needed to enforce Dodd-Frank. The law requires the commission’s staff for the first time to oversee swaps, a type of derivative. The industry is seven times the size of the futures business now under its jurisdiction, Mr. Gensler said.

“With $202 million, we can grow moderately,” he said. But “we need more resources to protect the public and oversee the swaps market.”

After the budget increases, regulators ended a yearlong hiring freeze. But both agencies say they are reluctant to significantly increase staffing for fear of having their budgets cut in October.

“Please keep in mind that this round of hiring will focus on the agency’s very highest priorities, and many divisions/offices may receive approval for very few, if any, of their priorities at this time,” the internal S.E.C. memo said. The memo further instructed officials to compile a list of the “top 10 priorities for hiring,” which will then be reviewed on a “case-by-case basis.”

The agency said it had not been able to fill nearly 200 positions this year owing to budget constraints. The S.E.C. had five open spots for experts in complex trading and received about 1,000 applicants for the roles; it could afford to hire just one person.

The agency also lacks money to adequately train the enforcement lawyers already on staff, Mr. Khuzami said. Some lawyers who wanted to attain their brokerage licenses to better understand the industry had to put off prep classes.

“I don’t think people realize how serious the problem is and how serious the consequences are,” said Harvey Pitt, who was chairman of the S.E.C. from 2001 to 2003.

The regulators, for instance, have had to slow down the adoption of Dodd-Frank rules. The S.E.C. has put off creating several offices mandated by the law, including a bureau that will oversee the credit rating agencies and a special office of “women and minority inclusion.”

The commodities agency, which planned to complete its 50 new rules by July, is now hoping to finish by early fall. Once the rules are complete, the agency will not have the funds to enforce them, Mr. Gensler said. Some 200 firms registering with the commission as swaps dealers may have to wait months for the agency to process their applications — unless it can hire several new employees in the department.

Regulators fear that Congress will soon slash their budgets, which could send the agencies scrambling to cut costs again — much as they did in recent months amid the threat of a government shutdown.

Until recently, employees from the commission were instructed not to order certain office supplies — items like three-hole punches and heavy-duty staplers. The ban was lifted after the new budget was instituted.

Some regulators were also paying for their own travel. When Mr. Gensler, a former Goldman Sachs executive, headed to Brussels to help the European Parliament create new derivatives rules, he paid out of his own pocket.

Another commissioner from the commodities agency who attended a conference in Boca Raton, Fla., paid for a night at the Sheraton using his family’s promotional points. Mr. Gensler attended via a videoconference.