Washington (CNN) House Speaker Paul Ryan's bombshell announcement that he will not seek re-election brings with it immediate and long-term political ramifications for his southeast Wisconsin district and the House landscape overall, where Democrats need to pick up 23 seats to gain the majority in 2019.

The most acute effect will be felt in Wisconsin's 1st Congressional District, which Ryan has represented since 1999. He already was facing a potential challenge from Democrat Randy Bryce, who had raised nearly $5 million for his campaign, including $2 million in the first quarter of 2018. The district, which includes Kenosha and Ryan's hometown of Janesville, is more favorable terrain for Democrats than the southwest Pennsylvania district Conor Lamb won in the March special election.

The Republican-aligned candidate in the recent Supreme Court race in Wisconsin won this district by five percentage points, despite losing the statewide race by more than 11 points.

That GOP performance is on par with Mitt Romney's margin in the district in 2012, but less than Donald Trump's 10-point spread there in 2016.

Bryce's bid is likely to lose a little enthusiasm without Ryan's name on the ballot, but the energy this cycle is clearly on the Democratic side.

More broadly, Republicans are also losing the party's best fundraiser for House candidates. Just this Monday, Ryan's campaign announced hauling in more than $11 million in the first quarter of the year, bringing its total raised to $54 million -- and transferring more than $40 million to the National Republican Congressional Committee to help other GOP candidates this cycle.

Then there are the optics of the decision. By announcing his retirement now, it sends a dire signal to Republicans that an already tough environment could get even more challenging.

Ryan's open seat moves from Likely Republican to Lean Republican, with the potential to become more competitive depending on who the GOP nominates to run in this district.

At the same time we are making a few other changes to our House race ratings.

Arizona

AZ-08: We are soon going to get yet another peek into the 2018 political landscape with an upcoming special election where Republicans are hoping the natural DNA of the district will be somewhat more resistant to the Democratic enthusiasm that toppled their candidates in Pennsylvania and Alabama.

The April 24 contest in Arizona's 8th Congressional District features Republican Debbie Lesko, a former state senator, and Democrat Hiral Tipirneni, an emergency room physician. The seat was vacated in December when GOP Rep. Trent Franks resigned amid sexual harassment allegations.

Democrats did not contest this House seat in 2016 or 2014.

At the presidential level, Trump defeated Hillary Clinton by 21 points in the district, which is made up primarily of the western Phoenix suburbs and chock full of retirees. Romney bested Barack Obama there by 25 points in 2012.

On the heels of Lamb's victory last month, Republicans aren't taking any chances. They've poured more than $600,000 into the race to keep it from flipping to the Democrats.

Democrats aren't nearly as bullish on this special election as they were about Pennsylvania. Republicans hold a 17-point advantage in voter registration in the district. Lesko remains a heavy favorite, but given how Democrats have overperformed in special elections the past year, this race should be closer than most would normally expect.

This race moves from Solid Republican to Likely Republican.

Ohio

OH-12: After the Arizona special election, all eyes will turn to this central Ohio district, which became open when Republican Pat Tiberi resigned in January to lead the Ohio Business Roundtable. The district is more urban than PA-18, which should make it a bit bluer. The inner ring Columbus suburbs are the kinds of places where Democrats expect to make gains this cycle. It's slightly less white than PA-18, and also a bit younger and with more college graduates. Trump got 52% of the vote here in 2012, underperforming Romney's 54% mark. There are crowded primaries on both sides, but the makeup of the district and the Democratic edge in enthusiasm mean this one is likely to get more competitive before August. This race moves from Likely Republican to Lean Republican.

Florida

FL-15: Ryan's isn't the only retirement announcement from Republicans Wednesday. Four-term Rep. Dennis Ross is leaving as well, opening up a seat in a district that includes the Tampa Suburbs -- and has the same partisan tilt on the presidential level as Ryan's district. There is a crowded Democratic primary there, with 31-year-old Navy veteran Andrew Learned holding a slight fundraising edge at this point. With Ross no longer on the ballot, this seat appears primed to become more competitive. This race moves from Solid Republican to Likely Republican.

New York

NY-11: Max Rose, a former non-profit healthcare executive and Army veteran, gives Democrats a candidate who could make inroads in this district, home to Staten Island. Rose also stands to benefit from a fractured Republican primary, with incumbent Rep. Dan Donovan running against former Rep. Michael Grimm, who served time in prison for felony tax fraud. For his part, Donovan is facing allegations he used his position to intervene in the arrest of his domestic partner's son on charges of heroin possession. This race moves from Likely Republican to Lean Republican.

Ohio

OH-14: Democrat Betsy Rader doesn't have a primary, giving her a clear shot at challenging GOP Rep. Dave Joyce in the 14th, home to the Cleveland and Akron suburbs. Like OH-12, this district has been more favorable to Democrats in previous elections than PA-18. Trump won it by 11 points in 2016, but Romney carried it by only three points in 2012. This race moves from Solid Republican to Likely Republican.

Wisconsin

WI-07: GOP Rep. Sean Duffy looks well-positioned to win re-election in northern Wisconsin, with more than $2 million in the bank at last check. But the recent state Supreme Court election in the Badger State suggests it might not be a sure thing, with a 20-point swing in favor of the Democrats from Trump's margin in 2016. Democrats think Bon Iver manager Kyle Frenette could give them a shot here. Frenette recently announced raising $250,000 in the six weeks since his campaign launched. This race moves from Solid Republican to Likely Republican.