Capital One announced on Monday that it was buying Discover Financial Services, in a $35 billion deal to combine two of the nation's largest credit-card firms. But experts say it will take at least a year for the merger to be completed, and there's already pushback from advocacy groups and lawmakers who fear consumers will face an even bigger "squeeze" in "a shrinking credit card market dominated by a handful of large players," per NBC News. The merger is set to face "gale-force headwinds from a Washington that is deeply skeptical of consolidation [and] anxious regarding consumer-facing issues in an election year," Isaac Boltansky of global financial services company BTIG says in a statement. More coverage: