WASHINGTON – Sen. John McCain moved closer to clinching the Republican presidential nomination Tuesday while Sen. Barack Obama increased his lead in the race for Democratic delegates.

McCain won at least 34 delegates Tuesday, with six delegates still to be awarded in Wisconsin and 16 in Washington state.

Overall, McCain had 942 delegates and former Arkansas Gov. Mike Huckabee had 245. It will take 1,191 delegates to claim the Republican nomination at this summer’s national convention.

With Tuesday’s results, Huckabee needs help from Mitt Romney’s former delegates just to remain a viable candidate. Romney has withdrawn from the race and endorsed McCain. But the former Massachusetts governor has little authority over his 253 delegates, most of whom will be free agents at the convention in St. Paul, Minn.

Obama won at least 38 delegates in Wisconsin, with nine still to be awarded. Sen. Hillary Rodham Clinton won at least 27. The Democrats also had 20 delegates at stake in the Hawaii caucuses, but none in the Washington state primary.

In the overall race for the nomination, Obama leads with 1,319 delegates, including separately chosen party and elected officials known as superdelegates. Clinton had 1,245.

The Associated Press tracks the delegate races by calculating the number of national convention delegates won by candidates in each presidential primary or caucus, based on state and national party rules, and by interviewing unpledged delegates to obtain their preferences.

Most primaries and some caucuses are binding, meaning delegates won by the candidates are pledged to support that candidate at the national conventions this summer.

Political parties in some states, however, use multistep procedures to award national delegates. Typically, such states use local caucuses to elect delegates to state or congressional district conventions, where national delegates are selected. In these states, the AP uses the results from local caucuses to calculate the number of national delegates each candidate will win, if the candidate’s level of support at the caucus doesn’t change.