According to one source, BGL is expected to hold chemistry meetings with up to eight agencies before compiling a shortlist of four.
BGL's other brands include Budget, Dial Direct, motorbike insurance specialist Bennetts and ibuyeco, the recently launched carbon neutral car insurance brand.
The decision to review follows a large hike in investment in the comparethemarket.com brand, which offers price comparison on motor insurance, and the recent appointment of Kal Samra as managing director of the business.
Samra, who previously ran the Bennetts operation, is expected to oversee a budget of £65 million across comparethemarket's marketing and web initiatives.
In June, Comparethemarket signed a £5 million deal with Channel 4 to sponsor the broadcaster's drama programmes. It also appointed VCCP to create the idents.
BGL is keen to talk to agencies with strong digital and direct credentials as the majority of its media activity is geared towards generating response.