The principal force, members of both parties said, is time.

In that role, he was a principal force in bringing modern management to the Pentagon.

Continued strength in manufacturing this year is expected to be the principal force keeping the country out of a recession.

The principal economic forces specific to Tobago are tourism and government spending.

Consciousness itself, he maintained, was the principal force in evolution.

Afghan units were the principal fighting force, supported by British forces.

The 10th Army was the principal force on the border with Egypt.

These two principal forces, economic gain and political security, have been behind enlargements since.

Here seemed to be the principal force of the attacking horde.

My discovery and analysis looked good even before the fact, and was at that moment the principal force driving the firm.