Use one of these samples. Please feel free to re-edit.

The Honorable [Senator's name]
U. S. Senate
Washington, DC 20510

#1
Dear Senator:

Please continue to take all needed steps to assure that Lithuania, Latvia and Estonia are invited to NATO membership. This will secure freedom and security and will be of benefit to the United States.

#2
Dear Senator:

The enlargement of NATO is in the long term interest of the United States and the Baltic States assuring peace and security. Please continue to support America's commitment to enlarge NATO.

#3
Dear Senator:

Please continue to support NATO membship for Lithuania, Latvia and Estonia and all other qualifying countries.

#4
Dear Senator:

The Baltic States have shown their readiness and ability to join NATO. Thanks for supporting NATO enlargement.

#5
Dear Senator:

The expansion of NATO is part of our President's anti-terrorism policy. We should support him.

#6
Dear Senator:

The United States supports a free Europe, united and whole. An expanded NATO will benefit the United States--world peace and stability. Please continue to support NATO expansion