WASHINGTON — The biggest outside groups backing Democrats and Republicans have paused broadcast television spending in Georgia’s Senate race, a notable shift in a contest once expected to be among the cycle’s most expensive. Neither the Republican-aligned Senate Leadership Fund nor the Democratic Senate Majority PAC bought broadcast television time in Georgia last week, according to ad-tracking firm AdImpact. It was the first week Senate Leadership Fund had been off the air in the race. Senate Majority PAC, aligned with Senate Minority Leader Chuck Schumer, said it will remain off the air in Georgia this week. Senate Leadership Fund did not say whether it would resume spending and declined to discuss its plans. The slowdown comes as public polling and fundraising show Democratic Sen. Jon Ossoff holding wide leads over Republican Rep. Mike Collins. The groups appear to be shifting resources toward contests they consider more competitive, including races in more reliably Republican territory. The pause concerns broadcast television spending by the two national super PACs; it does not establish that either campaign or other political groups have stopped spending in Georgia altogether. The state had been viewed as a major battleground, but the latest pullback suggests outside groups see less urgency in pouring money into the contest for now.