"backtrack by" is correct and usable in written English.
You can use this phrase to describe a situation in which someone goes back to an earlier point in a process or conversation. For example, "When the conversation became too heated, she decided to backtrack by changing the subject."
Something similar is involved with "Backtrack" by Susan Shortening, who used phosphorescent paint on a wall.
Bailiffs last week seemed to backtrack by giving Yukos another month to pay its $3.4 billion tax bill for 2000.
In his next brace of interviews, Miliband is bound to backtrack by arbitrarily listing recent television programmes and unconvincingly declaring them to be his favourite.
Kim expelled the dissenters from the ruling circles immediately after the attempt on his power, but was later forced to backtrack by the Soviets and the Chinese.
One is the possibility that the Fed will cut rates too much, sending the economy into overdrive next year and forcing it to backtrack by raising rates.
Johnson appeared to backtrack by promising in a BBC1 mayoral debate broadcast on Sunday night that he would try to lower fares from 2013.
The backtracking by Standard Chartered comes after a series of scandals involving Britain's largest financial institutions.
Backtracking by any one of them could sink the delicate process of untangling a complex war.
But he then backtracked by saying he would stand down only after a new government was formed.
The 1999 backtracking by the F.B.I. convinced him the government had burned out the Davidians and hidden the truth.
Analysts say that the backtracking by the French could lessen legislators' enthusiasm for graduated response systems in other countries, at least if they involve the threat of disconnection.
