By “long-term challenges to our fiscal health”, President George W Bush means the things that will slow government spending.
Explanation:
In his 2006 budget message, President George W Bush speaks about restraining the government expenditure in order to meet the near term and the long term fiscal challenges facing the country.
In order to reduce the fiscal deficit, President Bush had planned to implement his plan of cutting down the expenditure on numerous policies and schemes run by the government.