Although emerging markets outperformed Wall Street in the first quarter, U.S. stocks still performed well in early 2017, with chip makers, biotechs and financials leading the charge.

That combination is typical of the kind of market leadership one would want to see to forecast extended gains for the stock market into the second quarter.

But there are signs of weakness setting in. Already stocks have pulled back around 2 percent from their all-time highs scored earlier this year. That could be just the start.

First-quarter performance was largely driven by a few important factors: abundant confidence that the Trump/GOP economic stimulus agenda would sail through Congress; that corporate earnings would rebound 10-12 percent in 2017 even before any corporate tax reform; the economy would accelerate until it was strong enough to allow the Federal Reserve to 'normalize' (raise) interest rates at a quicker pace; and that global growth, likewise, would begin to quicken.

All of that seemed quite possible in the days immediately after the election and inauguration. However, the speed at which any of these stimulants may pass is now in open question – which puts future gains at risk.

The Trump Administration's ham-handed approach to moving its agenda through Congress shows no signs of letting up.

The failure of the President and a GOP-led Congress to "repeal and replace" the Affordable Care Act, was not just a legislative failure, it also fractured a Republican coalition needed to push through all other agenda items, from tax reform to future budget agreements.