WASHINGTON (Reuters) - Citing concerns about the U.S. economy, President Bush intervened on Monday in the West Coast port lockout by appointing a fact-finding board of inquiry, taking the first step toward ordering union workers back to the docks.

"Out of concern for the economy and jobs, the president this morning signed an executive order to create a board of inquiry," White House spokesman Ari Fleischer said.

The board would do fact-finding on the dispute, a process that could take a week. The White House must then try to convince federal courts that the dispute would "imperil the national health or safety." If the courts agree, they can order the ports to reopen and keep running for up to 80 days.

Before the talks to resolve the impasse broke down on Sunday, the White House appeared reluctant to intervene to put the 10,500 members of the International Longshore and Warehouse Union, ILWU, back on the docks, which port employers locked indefinitely on Sept. 29.

Administration officials feared intervention using Taft-Hartley would fail and could result in a backlash by organized labor against Republicans in the Nov. 5 congressional elections.