LONDON -- The evaporation of trust in lawmakers as a result of the U.K.'s expenses scandal could make it more difficult to achieve the shared sacrifice required to repair the fast-deteriorating public finances.

With the U.K. government forecasting that its debt will soar to 80% of gross domestic product by 2014 as the country suffers its deepest recession in decades, fixing the public finances will be the dominant policy challenge for years to come.

The last 10 days has seen a string of revelations that lawmakers from all parties milked the parliamentary expenses system for their own personal gain. The allegations have led to lawmakers being suspended, a ministerial resignation and police investigations. Tuesday brought the most significant casualty to date. Michael Martin, speaker of the House of Commons, resigned, becoming the first holder of the office to be forced out in over three centuries. The speaker umpires debates and is responsible for the office that oversees expenses. (See related article.)

In the near-term, the scandal could destabilize an unpopular Labour government whose grip on power is weakening after 12 years in office.

In the longer-term, evidence of widespread wrongdoing among lawmakers will make it harder for future governments to persuade taxpayers to pay more. A future government may therefore have to lean more heavily on spending cuts than it would otherwise have done in order to trim its debt.

"I think taxpayers around the country have been absolutely shocked and horrified by the recent events," said Susie Squire, head of campaigning at the Taxpayer Alliance, a group dedicated to lower taxes and eliminating government waste. "That's very important because politicians will need some more authority to rein in public spending and help kill our budget deficits."

While popular outrage has focused for most of the last year on incompetent bankers who've received golden parachutes, anger has recently shifted to politicians following a string of revelations about expense claims that range from extravagant to possibly larcenous.

In most cases, the reports have shown lawmakers taking advantage of the system rather than breaking the rules, although some claims do seem to cross the line. There was a claim worth several thousand pounds for fixing the pipes beneath one lawmaker's tennis court, while some lawmakers "flipped" the house they listed as their second home in order to claim expenses on both their main and backup houses.

Last week, the scandal drew first blood. A Conservative lawmaker resigned as aide to party leader David Cameron over embarrassing reports about his claims. The parliamentary party of Prime Minister Gordon Brown has suspended two lawmakers over claims they filed expenses on mortgage interest payments for loans they had already repaid.

On Friday, Justice Minister Shahid Malik became the first cabinet minister to step down as he fought to clear his name over an investigation into his rental arrangements. A cabinet minister was heckled and jeered on a popular political show and a number of lawmakers have had to hire police protection for their homes.

There could hardly be a worse time for public confidence in politicians to hit rock-bottom.

Under last month's budget, the government forecast one of the tightest public spending squeezes since 1945, with expenditure increases of just 0.7% per year from 2011. Adjusted for inflation, spending will fall, something that didn't even happen under Margaret Thatcher in the 1980s.

That means severely constrained spending on education, health and other key public services and minimum pay increases for heavily unionized public workers.

So far, credit-ratings agencies believe U.K. governments will have the political authority to bring spiraling public debt under control. Both Moody's and Standard & Poor's maintained the U.K.'s Triple-A credit rating after the budget despite projections of spiraling debt.

As S&P put it in its most recent "Full Analysis" report, because of its centralized political system and large parliamentary majorities, "the U.K. has a greater ability to respond quickly to external shocks than any of its peers."

That confidence may not be misplaced. Even under the fragile government of former Prime Minister John Major from 1992 to 1997, the public finances were mended after the previous recession in the early 1990s, although that improvement came at the start of a long period of extraordinary global growth.

Peter Kellner, president of polling firm YouGov, notes that in the 1990s the Conservative government saw several ministerial resignations and two former lawmakers end up in prison. "What is different this time is that the public has the impression that the whole of the political class has their snouts in the trough," he said. "I can't think of a time ... when the political classes were so widely despised."

The crisis could also have concrete near-term consequences. A YouGov poll last Friday showed falling support for both main parties, with Mr. Brown's Labour party slipping to a record low 22%.

June 4 sees European and local election and the polls suggest Labour could come in fourth, behind even the anti-European U.K. Independence Party. That's a result that could trigger fresh speculation about a leadership challenge to Mr. Brown from within the party.

On Monday, Conservative party leader Mr. Cameron piled the pressure on Mr. Brown, saying he should call an election straight after the June 4 vote.

While Mr. Brown is most unlikely to do that, he could still be vulnerable.

YouGov's Mr. Kellner said the scandal will make anxious Labour lawmakers readier to defy party whips on key votes, increasing the odds of a government defeat on a major bill. That would leave Mr. Brown staring over the political precipice.

Write to Laurence Norman at