Small part. Seing Brown's ads (over and over and over again - just like Coakley's) the emphasis was on financial matters and opposition to "the political machine". The financial matters he mentioned the most were the cost of the proposed health care legislation and taxes.

In all his ads, I only really remember one line about 'security' and it had to do with whether or not the Constitution covers terrorists. It was vague and quick. Everything else was about how a vote for him was a vote for a human being, not a 'delegate'.