Palin campaigned on ethics reform in the 2006 election, defeating incumbent Gov. Frank Murkowski in the Republican primary and a former two-term Democratic governor, Tony Knowles, in the general election.

She enjoyed an extended honeymoon with lawmakers and voters alike. Her popularity was in the 80 percentile range, even though that fell after the bruising, partisan presidential campaign.

Palin’s delivery of two weeks’ notice rattles a Republican Party plagued with setbacks in recent weeks, including extramarital affairs disclosed by two other 2012 presidential prospects, Nevada Sen. John Ensign and South Carolina Gov. Mark Sanford.

Ensign, a member of the Christian ministry Promise Keepers, stepped down from the Senate Republican leadership last month after admitting he had an affair for much of last year with a woman on his campaign staff who was married to one of his Senate aides. Ensign later disclosed he had helped the woman’s husband get two jobs during the affair.

A government watchdog group, Citizens for Responsibility and Ethics in Washington, wants the Senate ethics committee and the Federal Election Commission to investigate.

Just days after news of Ensign’s affair broke, Sanford admitted an affair with a woman in Argentina. Some lawmakers are now calling for his resignation. Before the admission, Sanford had been missing from the state for five days visiting his lover. He had slipped his security detail, lied to his staff about where he was and failed to transfer power to the lieutenant governor in case of a state emergency.

Sanford admitted he also saw the mistress during a state-funded trip to Argentina last year. He promised to reimburse the state for part of the trip’s costs. The state Commerce Department said the trip itinerary originally included only Brazil, but the governor requested economic development meetings in Argentina.

The GOP troubles seem to have left two prominent 2012 prospects, former House Speaker Newt Gingrich and 2008 presidential hopeful Mitt Romney, unscathed, however.