The phrase "a reliable ally of" is correct and usable in written English.
It can be used to describe someone or something that is consistently supportive or dependable in a relationship or partnership.
Example: "Throughout the years, she has proven to be a reliable ally of the organization, always stepping up when needed."
Alternatives: "a trustworthy partner of" or "a dependable supporter of".
He was also a reliable ally of the West.
Not long ago, Mr. Bloomberg was viewed as a reliable ally of labor.
If Orban were a reliable ally of the United States, then perhaps his democratic backsliding could be excused.
While Justice White is usually a reliable ally of the Court's conservative bloc, he has aligned himself with the liberal Justices in several important school desegregation cases.
The United Arab Emirates is a reliable ally of the United States in the Middle East, and a major buyer of American military equipment.
Jewish leaders say that while they are supportive of President Bush because he has been a reliable ally of the Israeli government, they have become increasingly fearful of a backlash if the war goes badly.
If Ms. Hochsprung was a relatively new face in the school, Ms. Sherlach was a fixture, a reliable ally for generations of children in need of counsel.
Since then, the United States has reduced the pressure on Hosni Mubarak for real democratic reforms, in part because it regards him as a reliable ally and guarantor of stability in the Middle East.
When the first protesters appeared in Tahrir Square, Mrs. Clinton, working off the traditional American script that portrays Mr. Mubarak as a reliable ally in need of quiet, sustained pressure on human rights and political reform, said, "Our assessment is that the Egyptian government is stable and is looking for ways to respond to the legitimate needs and interests of the Egyptian people".
We were respected by our friends and could be counted on as a reliable ally in times of crisis.
It appeared that the muscle for the anti-Spitzer operation might emerge from the city's labor unions, which view Mr. Stringer as a reliable ally, and are wary of the less predictable Mr. Spitzer, who has not hesitated to confront them in the past.
