• There is reason to believe that this problem will not be difficult to control.
• There are reasons ( or grounds ) to assume that ...
• There is reason to believe that this problem will not be difficult to control.
• There are reasons ( or grounds ) to assume that ...
Циммерман М., Веденеева К.. Русско-Английский научно-технический словарь переводчика. Russian-English scientific dictionary for translators. 2012