Republican Gov. Bob McDonnell of Virginia and Democratic Gov. Martin O’Malley of Maryland, normally allies on regional issues, on Sunday squared off for the first time as the leaders of their national parties’ efforts to win state elections next year. McDonnell, chairman of the Republican Governors Association, said reining in government spending is the key to economic prosperity. O’Malley, chairman of the Democratic Governors Association, pushed for greater spending on education and infrastructure, saying the government had to do more as unemployment hovers stubbornly above 9 percent.