Trump gives nod to vulnerable GOP Sen. McSally with bill signing

President TrumpDonald John TrumpPapadopoulos on AG's new powers: 'Trump is now on the offense' Pelosi uses Trump to her advantage Mike Pence delivers West Point commencement address MORE sought to boost Sen. Martha McSallyMartha Elizabeth McSallyOn The Money: Senate passes disaster aid bill after deal with Trump | Trump to offer B aid package for farmers | House votes to boost retirement savings | Study says new tariffs to double costs for consumers Senate passes disaster aid bill after deal with Trump Senate defense bill would make military sexual harassment standalone crime MORE (R-Ariz.) with a Twitter shout out Tuesday as the Arizona Republican faces a tough reelection battle against astronaut and gun control activist Mark Kelly.

“Just signed a critical bill to formalize drought contingency plans for the Colorado River. Thanks to @SenMcSallyAZ for getting it done. Big deal for Arizona!” Trump tweeted Tuesday that McSally retweeted.

The law Trump signed codifies an agreement between Arizona, Colorado, Wyoming, Utah, California, New Mexico and Nevada to establish voluntary water conservation measures as the states try to manage prolonged drought conditions and regional impacts of climate change.

The Arizona Republican is running next year to serve the remaining two years of the late Sen. John McCainJohn Sidney McCainClimate change is a GOP issue, too It's Joe Biden's 2020 presidential nomination to lose Meghan McCain on Pelosi-Trump feud: 'Put this crap aside' and 'work together for America' MORE’s (R) term. McSally was appointed to the Senate in December after McCain’s death in August, with former Sen. Jon Kyl (R) serving in the interim months. However, she was defeated by Democrat Kyrsten Sinema in the 2018 race to replace retiring Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeSen. Coons examines Amazon's privacy and data security practices for Alexa devices Oil companies join blitz for carbon tax The Hill's Morning Report - White House, Congress: Urgency of now around budget MORE (R).

Sinema’s victory made the Grand Canyon State a top priority for Democrats, who have successfully recruited a top-tier challenger in Kelly.

Kelly announced earlier this month he raised a staggering $4 million in the first quarter of 2019, with the average online contribution amounting to $25. The Arizona Democrat also has high name recognition as a former astronaut and husband to former Rep. Gabrielle Giffords (D-Ariz.), who narrowly survived a shooting in 2011. The two have since become high-profile advocates for gun control reform. 

McSally hauled in about $2 million in the first quarter of 2019, according to a Federal Election Commission filing.

Republicans hope to defend their 53-47 Senate majority next year as a handful of GOP incumbents face tough Democratic challengers in states like Colorado, Maine, North Carolina, Iowa and Arizona.