Updated

Massachusetts Democratic leaders appear to be rallying support behind Rep. Edward Markey to avoid a nasty primary and potential upset in a likely special-election race for the open seat of Sen. John Kerry.

Kerry, President Obama's nominee for secretary of state, Victoria Reggie Kennedy, the widow of the late Sen. Edward M. Kennedy, and the Democratic Senatorial Campaign Committee issued statements Friday in support of Markey, the Boston Globe reported.

Kerry, chairman of the Senate Foreign Relations Committee, still faces Senate confirmation hearings but is expected to pass.

Markey, a 36-year House veteran, announced earlier this week that he would run for Kerry's seat if the senator is confirmed.

His support sends a signal to other potential Democratic candidates, including Reps. Michael Capuano and Stephen Lynch, to stay out of the race.

The potential candidates were reportedly upset by the perceived power play but don't appear willing to step aside, a top Democratic operative told the newspaper.

Democratic Rep. Niki Tsongas, considered a strong potential candidate, announced Friday that she would not challenge Markey for the party nomination.

The leading Republican candidate would likely be Sen. Scott Brown who lost his reelection bid last month by 8 percentage points to Democratic challenger Elizabeth Warren. However, Brown has not said whether he would make another run in the heavily Democratic state.

If and when Kerry officially gives up his seat, Gov. Deval Patrick has 145 to 160 days to set a date for a special election. The Democratic governor will appoint an interim senator to fill the seat until the election results are counted.

The effort to clear the field suggests top Democrats want to avoid a primary battle that would drain resources and perhaps create inter-party rancor.

Brown was elected to Congress in a January 2010 upset victory, after a tough Democratic primary. And Democrats think he could win again, especially if few voters turnout.