Inside the high-stakes fight for a North Shore congressional seat and why it matters for Mass.

Inside the high-stakes fight for a North Shore congressional seat and why it matters for Mass.

When he announced he was running for U.S. Senate last fall, U.S. Rep. Seth Moulton did more than add fuel to his own political ambitions.He also sparked a complete free-for-all for his North Shore-based congressional seat. That’s because open seats — for any elected office — tend to be rarer than Loch Ness Monster sightings in the Bay State.