From Louis Jacobson’s update, “Democrats Poised to Eat Into GOP’s Lead in State Legislatures” at Governing:

According to our first handicapping of state legislatures this cycle, Republicans currently have more chambers at risk, 10, than the Democrats’ seven. Connecticut’s tied Senate is also at risk of a party switch…That adds up to 18 competitive chambers at this point — identical to the number of competitive chambers in 2014, which was the most recent election cycle to feature a strong partisan wave. It was the Democrats who were on the run back then, with 11 Democratic-held chambers rated competitive compared to just seven for the Republicans.

During past wave elections, we’ve tended to see additional chambers become vulnerable to a party switch as time goes on, almost always for the party facing the wave. So unless the political environment changes significantly, expect the number of competitive Republican chambers to rise as November approaches.

However, Jacobson also notes,

Currently, the GOP holds more than two-thirds of the nation’s legislative chambers — 66 in all, compared to 31 for the Democrats. For housekeeping’s sake, this tally counts New York’s Senate as Republican and Alaska’s House as Democratic; both states are led by bipartisan coalitions. Meanwhile, Nebraska’s unicameral legislature, which is nonpartisan, isn’t included in our count.

A mere wave election won’t do it for Democrats. It will take a blue tsunami to flip, or even level those numbers.

Governing’s “assessment is based on interviews with dozens of state and national political sources.” As Jacobson observes,

All told, we rate five Republican-held chambers as tossups: the Colorado Senate, the Maine Senate, the New Hampshire Senate and House, and the New York Senate.

We rate an additional five GOP-held chambers as lean Republican — not yet as vulnerable as the tossup chambers, but worrisome for the GOP nonetheless. Those chambers are the Arizona Senate, the Florida Senate, the Iowa House, the Michigan House and the Wisconsin Senate.

We don’t rate any Democratic-held chambers as tossups for now, but we do consider seven of them to be in the lean Democratic category: the Alaska House, the Colorado House, the Connecticut House, the Delaware Senate, the Maine House, and the Washington Senate and House.

Further,

We see seven chambers currently rated likely Republican that are worth watching for possible movement toward the Democrats. They are: the Arizona House, the Iowa Senate, the Michigan Senate, the Minnesota House, the North Carolina Senate, and the Pennsylvania Senate and House.

All in all, Democrats have reason to feel optimistic about gains at this point. Still, it’s worth injecting a note of caution. Even a net switch of 14 chambers toward the Democrats — the absolute maximum shift we can envision at this stage of the campaign — would still leave Republicans with a national edge in chambers of 52-46. So don’t expect the Democrats to seize a majority of state legislative chambers in 2018 alone.

Jacobson gets down to state by state cases with some relevant details. But Democrats can take some encouragement from recent state legislative special elections. In his Politico post, “‘Let the blue wave continue’: Democrats notch 4th Florida bellwether win,” Marc Caputo writes,

On Tuesday, in Florida’s 114th House District in Miami, Javier Fernandez beat Republican Andrew Vargas by about 4.1 percentage points, despite being outspent by at least 2-1 in a swing seat where voters split their tickets between both parties in the 2016 elections.

…Fernandez’s win follows a shocking February victory by Democrat Margaret Good in Florida’s 72nd House District, which voted for President Donald Trump. Democrats also won Florida’s 40th Senate District in Miami-Dade and St. Petersburg’s mayoral race. Those last two elections had Democratic-leaning electorates with significant minority populations, unlike the 72nd in Sarasota and, to a lesser degree, the 114th District.

The win was also big for Florida Democrats because they finally started to build a bench by electing their second Cuban-American Democrat from Miami-Dade County to the Florida Legislature, where the 42-year-old Fernandez will join state Sen. José Javier Rodríguez.

“While the Florida House is likely to stay Republican for years,” Caputo writes, “Fernandez’s win bolstered hopes that Democrats could be closer to taking back the Florida Senate if they can flip five seats in the 40-member chamber.”

Florida’s state legislative races may well provide an instructive test of just how fed up Florida parents are with gun violence in their state, and who they want to hold accountable. At The Monitor, Patrick Jonsson notes that 91 percent of Florida’s Republican lawmakers have an “A” rating from the NRA.

Florida did enact a statewide measure that raised the minimum age for buying guns from 18 to 21, set a three-day waiting period, and banned bump stocks. However, opinion polls show strong nation-wide support for a ban on sale of assault-style weapons, and the Florida election will see if the modest reforms are enough in a state that has experienced two massacres in recent years.