Boston ? As the nation’s governors gather for a convention here this weekend, the challenge facing state leaders is familiar: balancing budgets as revenues decline and the demand for government resources rises.

But for a sizable number of those in attendance at the National Governors Association’s summer meeting, the task of navigating those challenges will not be theirs much longer.

By next year, no fewer than 24 states will have new governors. Most openings are a result of term limits, but at least a half-dozen more governors chose not to seek re-election in a turbulent political environment.

In addition, one incumbent already has been defeated in a primary election, and many more face difficult races this November.

Even the man who is to take over as the NGA’s new chairman, West Virginia’s Democratic Gov. Joe Manchin, could leave his seat early to run for the state’s vacant Senate seat. As a result, the final turnover rate could surpass 30 governorships, believed to be a historic high.

“It’s quite significant at a challenging time to the states,” said Republican Jim Douglas, outgoing chairman of the group and the soon-to-be former governor of Vermont.

The turnover could be significant on a political level as well. Democrats now have a 26-24 majority of statehouses. But 37 states are holding gubernatorial elections this fall. The non-partisan Cook Political Report rates 12 of those races as potential Republican victories — including four currently held by Democrats.

Of seven states seen as potential Democratic wins, only one would represent a pickup from Republicans.

The financial challenges faced by governors are a focal point of the conference. A study by the National Conference of State Legislatures found that states were forced to grapple with combined budget deficits of nearly $150 billion in 2009. The budget picture is growing worse, as stopgap federal aid is due to expire and an anticipated recovery has been slow to materialize.