WASHINGTON — A pair of conservative judicial advocacy groups have launched campaigns in Louisiana to push the confirmation of Kyle Duncan to a seat on the 5th U.S. Circuit Court of Appeals.

The push behind Duncan, a conservative attorney and LSU graduate in his mid-40s who's amassed a sterling resume in D.C. dotted with high-profile Christian culture battles, comes amid hints of possible discord between the state's two U.S. senators over Duncan's nomination by President Donald Trump.

U.S. Sen. John Kennedy, a Madisonville Republican, hasn't yet returned a so-called "blue slip" for Duncan indicating whether he supports the attorney's nomination. The slips give both of a nominee's home-state senators a chance to offer opinions on the nomination.

The Senate's Judiciary Committee, the panel which must clear federal judicial appointees before sending the nominations to the full Senate for confirmation, has traditionally deferred to those senators when considering nominees, giving home-state lawmakers significant influence in the process.

"I haven't made a decision yet," Kennedy said Monday when asked about Duncan's appeals-court nomination. The senator declined to elaborate on his decision-making process.

Sen. Bill Cassidy, R-Baton Rouge, has submitted a blue slip supporting Duncan's nomination. Cassidy confirmed his support of Duncan to The Advocate on Tuesday but declined to comment on Kennedy's deliberation.

The New York Times highlighted Kennedy's lack of a blue slip on Duncan in a Sunday front-page story on the increasingly heated Capitol Hill showdowns over President Trump's picks for federal judgeships.

The Times noted three other home-state senators who hadn't returned blue slips on appellate-court nominees, all Democrats. Kennedy was the lone Republican identified by the paper.

Duncan, a Baton Rouge native, earned his law degree at LSU and has built a reputation as a talented litigator with a penchant for controversial social-conservative causes.

Duncan has spent much of his legal career outside of his home state, most recently spending two years as general counsel for the Becket Fund for Religious Liberty, a D.C.-based conservative advocacy group, before launching his own private practice in the nation's capital.

But Duncan has also done considerable work for the state of Louisiana over the past decade.

Former Gov. Bobby Jindal hired Duncan to defend a controversial state law that would've required doctors who perform abortions to be affiliated with a hospital. He also spent three years working primarily on appellate cases for the Louisiana Attorney General's Office after a similar stint in Texas.

Duncan is perhaps best known nationally for his lead role representing the owners of the Hobby Lobby store chain in a successful challenge against a federal rule requiring employer health-insurance to cover birth control. Duncan successfully argued that the requirement infringed on the religious beliefs of the stores' owners.

The Americans United for Life, which bills itself as the legal arm of the anti-abortion movement, is among the groups backing Duncan's candidacy in a campaign in Louisiana.

The Judicial Crisis Network, a conservative advocacy group focused on federal judicial appointments and decisions, is the other. The group's ad features state Attorney General Jeff Landry praising Duncan as "one of the best lawyers of his generation."

Neither group specifically mentions Kennedy. Carrie Severino, JCN's chief counsel and policy director, said the senator's continued indecision on Duncan — whom Trump nominated in September — didn't necessarily motivate the group's six-figure campaign.

The group has launched similar campaigns in states with Democratic senators urging confirmation of other federal appeals court nominees. But Severino said they're also backing nominees, like Duncan, "we know are going to face Democratic opposition."

Senate Majority Leader Mitch McConnell has made confirming Trump's judicial nominees a top priority over the last several weeks, pushing through a number of district- and appeals-court names while publicly complaining about procedural rules Democrats have exploited to slow down the process.

Duncan has not yet been scheduled for a hearing before the Senate Judiciary Committee. A spokesman for Sen. Chuck Grassley, R-Iowa, the committee's chairman, said Tuesday he had no update on Duncan's nomination.

Kennedy, a member of the committee, also demurred when asked if he knew when Duncan's confirmation process might get moving again.

"I have no idea," Kennedy said, before adding with a smile, "I just work here."

An earlier version of this article misidentified one of the groups actively campaigning on behalf of Duncan's nomination as the National Right to Life Committee. Although that group supports Duncan's nomination, it was American United for Life that recently launched a campaign.

Follow Bryn Stole on Twitter, @BrynStole.