From VOa News:
The crowd at the Romney election party in Washington was predominantly white and universally disappointed.
While Romney won a majority of white voters in the election, he had less success in winning over women, younger people and minority voters.
Republican strategist Ford O’Connell says that will have to change.
“I think the Republicans have to recognize that they have to get beyond their echo chamber and actually help make inroads with other groups," O'Connell says, "because there are a lot of pre-conceived notions about Republicans in some minority groups harbor, and it’s up to Republicans to reach out and sort of change that perception.”
When Ronald Reagan won the presidency in 1980, white voters made up 85 percent of the electorate. This year they only made up 72 percent.

In addition to minority voters, Republicans face a major challenge in drawing more support from younger voters, pollster Scott Rasmussen says.
My questions:
1.What does "echo chamber" mean?
2.What does "make inroads" mean?
3. What does "harbor" mean?
4.Is it suppose to be "of"?
Thanks.