Answer: True.
Most major interest groups find it very necessary to have a lobbyist. This is because they need a person that communicates their goals and purpose to congress, this helps so that the people of congress know the interests of a portion of the population and can act on this. Most of the times, the interest groups are seeking a specific law or bill to be passed so they send the lobbyist to speak and pressure congress. Forms of getting congress to pass a bill include, money offering or "donations" which can be known as "bribery".
Hope this helps, best of luck and Happy New Years!!! Have a wonderful weekend :) xx